Use convenience function to checksum

That coreboot uses the IP checksum is an artifact, not a deliberate
requirement to be compatible with the Internet Protocole suite. Use
a wrapper to abstract the computation of coreboot's checksum.

Change-Id: I6491b9ba5efb9ffe5cb12a6172653a6ac80a1370
Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
Reviewed-on: http://review.coreboot.org/497
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
2 files changed