STM32L4 FLASH, DFSDM: option bytes, JEXTSEL bits, ADC1 output to DFSDM chips change

* STM32L4 FLASH: add function for modifying device option bytes

* STM32L4 DFSDM: add JEXTSEL bits, ADC1 output to DFSDM chips change

    ST's documentation hints that ADC output can be routed to DFSDM
    on some STM32L4X3 chips, but I got confirmation from tech support
    that this is just a documentation error so remove this from Kconfig.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

fs/vfs:  file_write() and file_pwrite() are internal OS interfaces and should not report errors via the errno

Addes support for read-only routing tables.  Prior to this change, routing tables were only support in RAM and had to be initialized with explicit logic to add the necessary routes to the routing table.  With this change, routes may be defined in the pre-initialized, read-only routing table provided by the board-specific logic

This would be particularly useful, for example, in the case where there is only a single network adaptor and you want all output packets to go to the single adaptor in all cases.  So for that behavior you could add a read-only routing table to the board-specific long that contains a single entry, the default route: 0.0.0.0/0.

Squashed commit of the following:

    net/route:  RAM and ROM routing tables build correctly in all IPv4 and IPv6 configurations.

    net/route: Verify IPv6 ROM route build; Make number of ROM routes a variable, not a configuration item.

    net/route:  Add initial support for ROM-base, read-only routing tables.

    net/route:  Adjust and generalize some structures, rename some functions, and add configuration and build support that will eventually support read-only routing tables.

    net/route:  Some initial though experiments on use of a fixe, read-only routing table

STM32 PWR:  Adds stm32_pwr_getsbf and stm32_pwr_getwuf functions that return the standby flag and the wakeup flag PWR power control/status register.

ROMFS for STM32F4 Discovery board

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Fixed directory unlocking in tmpfs_opendir

Approved-by: Gregory Nutt <gnutt@nuttx.org>

drivers/usbdev/cdcacm.c:  Change ordering of some operations to avoid races; Add missing uppder watermark logic that is normally in serial_io.c but must be duplicated in cdcacm.c; update comments

drivers/usbdev/cdcacm.c:  Fix confusion between flow control being enabled and being active.  Different things

drivers/usbdev/cdcacm.c:  Add some missing logic when flow control is disabled.  Also make sure that the flowcontrol and rxint can handle being re-entered when cdcacm_release_rxpending() is called.

Build break fix: define PWM_TIM2_CH1CFG for channel 1 PWM

Approved-by: Gregory Nutt <gnutt@nuttx.org>

drivers/usbdev/cdcacm.c:  Add a failsafe time to assure that the RX pending queue cannot stall indefinitely.  I can imagine a corner case where the serial driver's RX buffer is full and it stops accepting data and where all of the read requests are queued and there is not event to restart RX processing.  I am not sure that that scenario can really happen, but the failsafe timer gives me peace of mind.

    drivers/usbdev/cdcacm.c:  Change design for queuing RX packets that cannot be processed.  Previous design had a logic problem that could cause data loss.

    drivers/usbdev/cdcacm:  Fixes one of two know design issues.

    drivers/usbdev/cdcacm:  First attempt to plug data leak in input flow control design.  Still missing a few things.

    net/socket/recvfrom.c: Check fromlen integrity before using it.

    net/socket/net_sockets.c: Always check for valid psock before using.

    net/tcp/tcp_send_unbuffered.c:  Avoid using psock beforing checking its integrity.

    sched/timer/timer_create.c: Fix watchdog resource leak if cannot allocate a new timer.

drivers/net/rndis.c:  Eliminate a warning when assertions disabled. Consequence of replacing assert() with DEBUGASSERT().

drivers/usbdev/rindis.c:  Change some naming to conform with coding standard.  Use DEBUGASSERT vs. assert so that the assertions can be disabled.

From: Sakari Kapanen <sakari.kapanen@optofidelity.com>
Date: Sun, 24 Sep 2017 13:19:25 +0300
Subject: [PATCH] ICMPv6: fix router advertisement

Fixes several errors preventing icmpv6_radvertise.c from being compiled. Fixes conversions to network byte order (namely vlifetime, plifetime, mtu).

IPv6 source address is set to link-local IP address instead of the address in the netdev structure. This is in compliance to RFC 4861. RA didn't work on Linux before this change.

Finally, router prefix and prefix length are derived from the IPv6 address and netmask in the netdev structure. This seems to make more sense than using a predefined, separate prefix from the config.

drivers/usbdev:  CDC/ACM should reset all 'irregular' notifications to zero after sending the SerialState packet.