Do not return hardcoded numerical values to communicate succes/failure, but
instead use an enumeration.
Change-Id: I742b08796adf136dce5984b702533f91640846dd
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/4265
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>