paycheck: Disambiguate hash error messages.

Before we've been emitting the exact same error message when failing to
verify the hash of either pre- or post-update partition. This prefixes
the partition name with "old" or "new", respectively.

BUG=chromium:510909
TEST=None

Change-Id: Icf302d0a3b26d3f9860c4ccb03dba38493296794
Reviewed-on: https://chromium-review.googlesource.com/286143
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed