configs:  Review all implementations of board_lcd_initialize().  The NuttX convention is that all internal functions that return errors as an 'int' must return a negated errno value on failure and a non-negative value on success.  Most were right but eight of them had cloned logic that returns 1 on success and zero on failure... both of which are interpreted as success by the caller since they are non-negative.

include/nuttx/wireless:  Add support for the rest of the IOCTL options needed to support apps/wireless/bluetooth/btsak.  This is only the IOCTL command definitions.  The IOCTL command implementation is still missing.

arch/arm/src/nrf52:  Add watchdog timer drivers.  Includes significant updates from Alan Carvalho de Assis <acassis@gmail.com>

drivers/net: Add TAP (network bridge) mode to tun.c

In previous implementation, TAP mode did not handle a packet
correctly. Also, the driver did not set the link layer type and
could not assign the interface name. This PR changes fix such
issues and supports TAP mode correctly.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

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

drivers/wireless/bluetooth:  Partition bt_uart.c adding bt_uart.h and bt_uart_generic.c.  This will now permit adding HCI UART drivers that have custom initialization requirements.. such as parts the need to download a configuration file to the HCI UART before they are usable.

configs/Kconfig:  Fix some breakage inflicted on the Kconfig file by the i.MX RT merge.  Fix some coding standard problems in hymini-stm32v board support.

wireless/bluetooth:  Add support for IOCTL commands to perform GATT discovery and obtain the results.

include/nuttx/wireless:  Remove bogus name from structure.  This was left over from a previous change and had me confused for awhile.

wireless/bluetooth:  Remove Rx kernel thread.  The operation of dispatching messages can be performed just as well on the high and low priority work queue.  The network driver operates the low priority work queue so that also integrates better with network frame reception.

Xbee: Adds a timeout to send logic to handle case where XBee module fails to respond to a Transmit request with a Transmit Status

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

stm32f7 fix CONFIG_STM32F7_STM32F77X define typo

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

arch/arm/include/tms570, arm/src/armv7-r, and arm/src/tms570:  Adds support for the TMS570LS3137ZWT and corrects seversl ARMv7-R and TMS570 issues

arch/arm/src/stm32 and drivers/wireless/bluetooth:  Fix some buffer management errors in HCI UART upper and lower halves.

net/sixlowpan:  Fix a nasty, byte-ordering/endian-ness problem.  The root cause has been found and corrected.  And a half dozen or so bandaid fixes were reverted.