integrity: ignore keys failing CA restrictions on non-UEFI platform

On non-UEFI platforms, handle restrict_link_by_ca failures differently.

Certificates which do not satisfy CA restrictions on non-UEFI platforms
are ignored.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-and-tested-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>