elog: Check for successful flash erase in elog_shrink

A parrot device with a bad flash part has been seen to hang
in the elog_shrink code becuase the flash was not successfully
erased and it gets stuck in a loop trying to shrink the log
and then add an event.

Change-Id: I8bb13dbadd293f9d892f322e213c9255c8e9acb3
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/56405
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/4186
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
1 file changed