Revert "omni: switch to sha256 checksum"

This reverts commit f0e22647c3aa6f44995ec8fea305d06d0a330c58.

Reason for revert: OpenDelta relies on md5sum

Change-Id: Ic3a56e77dc98d6d6e1e7da0b3e39c9aa12abd566
1 file changed