vboot/vbnv_flash: fix return value check for rdev_writeat()

The return value check was incorect and checking for failure
in the success path. Fix the return value check so that it
actually checks for success.

BUG=chrome-os-partner:56151

Change-Id: Ie7960b89a916dec261015c97c3e0552be56b5b5d
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/16303
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
1 file changed