wrs_main: check for stack overflow and detect reset

Add checking stack overflow and detecting reset to wrs. Code common for wrpc
and wrs is placed in system_checks.c and .h. Work is based on following
commits in wrc_main.c:
1704a668 main: check for stack overflow
7836c39e

 Optionally detect reset and print a stack trace

Additionally:
--update Kconfig to have a possibility to select CHECK_RESET also for switch,
  not only for node as before
--and _endram to ram-wrs.ld

When "stack overflow" occurs then message is printed once every second.
When reset occours then LM32 will print stack trace and reset once more.
NOTE: I couldn't get spll to work after reset, for sure problem is in
      ad9516 init function, but not only there.

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>