KEYS: Make use of platform keyring for module signature verify

KEYS: Make use of platform keyring for module signature verify

This patch completes commit 278311e417be ("kexec, KEYS: Make use of
platform keyring for signature verify") which, while adding the
platform keyring for bzImage verification, neglected to also add
this keyring for module verification.

As such, kernel modules signed with keys from the MokList variable
were not successfully verified.

Signed-off-by: Robert Holmes <robeholmes@gmail.com>
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Gbp-Pq: Topic features/all/db-mok-keyring
Gbp-Pq: Name KEYS-Make-use-of-platform-keyring-for-module-signature.patch