HACK: samsung: pm-check: Add runtime options to enable and panic

HACK: samsung: pm-check: Add runtime options to enable and panic

Add runtime options to enable, panic and switch between xor and crc
checks of memory.

Update the exclusions to ignore log_buf and sleep_save_sp

BUG=chrome-os-partner:15600
TEST=Tested that with pm_check_should_panic system panics after an
  error and continues running when not set
  Set and unset pm_check_use_xor - confirmed differences in time and
    difference in values for errors
  Set and unset pm_check_enabled, validated log messages for running or not
  Chanaged pm_check_chunksize, saw size of crc error blocks change
  Confirmed correct error messages with pm_check_printskips
  Confirmed suspend_stress_test still catches errors correctly

Change-Id: I4275782391de32378be2f717bd48852ffde634ce
Signed-off-by: Jonathan Kliegman <kliegs@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/36475
Reviewed-by: Michael Spang <spang@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>