image_signing: Don't create empty keyset subdir

updater4.sh uses the /keyset subdir from the firmware updater shellball
to indicate if it should use model specific keys or not.  This won't
work for any case where the signers haven't been updated with model
specific keys yet.

Changed the output for unibuilds to be consistent with non-uni builds
where the /keyset subdir won't be created if loem.ini doesn't exist on
the signer.

BUG=b:65128657
TEST=crrev.com/c/626718 and crrev.com/c/636344 test cases, which cover
both the shared and non-shared key use cases
BRANCH=None

Change-Id: I38db1385fa99ac4a9843a750c336c58b74b127b4
Reviewed-on: https://chromium-review.googlesource.com/642031
Commit-Ready: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Tested-by: C Shapiro <shapiroc@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jason Clinton <jclinton@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed