mmc: Update u-boot if needed

Calculate a hash over the u-boot image file and the mmc device
where u-boot is stored to determine if it needs to be updated.

Tested: Verified that after the mmc device is updated, an update
to the same image does not rewrite the device where u-boot is.

Change-Id: I9f3cb8cc639512c02030b7be34845a67f3e15319
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
1 file changed