procfs: Fix incorrect uptime with CONFIG_SYSTEM_TIME64

Jira: PDFW15IS-45
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

sched: Fix CHILD_FLAG_EXITED in include/nuttx/sched.h

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

Jira: PDFW15IS-196
Jira: PDFW15IS-1109
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

USBMSC: Fix a wrong lun number issue

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

Jira: PDFW15IS-98
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

net: network drver now retains Ethernet MAC address in a union so that other link layer addresses may be used in a MULTILINK environment.

clock: Add new type ssystime_t for relative 64-bit ticks, change ticks<->time conversion functions to use ssystime_t

Add clock_resynchronize for better synchronization of CLOCK_REALTIME and CLOCK_MONOTONIC to match RTC after resume from low-power state.

Add up_rtc_getdatetime_with_subseconds under CONFIG_ARCH_HAVE_RTC_SUBSECONDS to allow initializing (and resynchronizing) system clock with subseconds accuracy RTC.

Move net/iob to drivers/iob so that the I/O buffering feature can be available to other drivers when networking is disabled.

procfs: Fix wrong member IDs are displayed when 'cat /proc/<pid>/group/stasus'.

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