re-sign-gsc: support supplying an image file

Take in an optional image arg, so we don't need to copy images into the
ti50 or cr50 build directories.

BUG=b:380145576
TEST=manual

Run in platform/cr50 and platform/ti50. Verify it generates an image.
./util/re-sign-gsc.sh $DEVID

Run in platform/cr50 and platform/ti50. Verify it resigns the supplied
image.
./util/re-sign-gsc.sh $DEVID ti50.bin|cr50.bin

Change-Id: I7dcbd9d45ebdcaf09e62aeefea8ab99c74c6ffdf
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/6042061
Reviewed-by: Vadim Bendebury <[email protected]>
Commit-Queue: Mary Ruthven <[email protected]>
Tested-by: Mary Ruthven <[email protected]>
1 file changed