Rename CONFIG_EXAMPLES_NXCONSOLE to CONFIG_EXAMPLES_NXTERM; rename CONFIG_NXWM_NXCONSOLE to CONFIG_NXWM_NXTERM

SAMA5D4-EK:  Add documentation/support for Rev E. board. Refresh NSH configuration.  Fix some build errors/warnings introduced with recent work with the knsh configuration

Move common/up_signal_dispatch.c to armv6-m, armv7-m, and armv7-a.  The armv7-a version needs to be different to handle the case where we are dispatch kernel mode signals when running under a user mode group