[coreboot] cross-repo-cherrypick and re-writing Signed-off-by's

Hi fellow coreboot developers, it was pointed out to me that I didn't do exactly what Chromium developers are used to (i.e. what util/scripts/cross-repo-cherrypick does) when picking patches to flashrom-stable. The major difference is that I didn't prepend Signed-off-by tags with an `Original-`.

[coreboot] [coreboot - Cleanup #421] Change API of functions taking hash as an argument

Issue #421 has been updated by Michał Żygowski. There may not be a strong need to have multiple hashes in the log entries yet. I have also recently spotted Intel fTPMs that can have only one PCR bank active at a time, so only discrete TPMs are capable of having multiple PCR banks active.