MokManager: Support SHA1 hash in MOK

Add SHA1 hash support and amend the code to make it easier to support
other SHA digests.
MokManager: fix the return value and type

There are some functions that the return value and the type
didn't match.

Signed-off-by: Gary Ching-Pang Lin <glin@suse.com>
MokManager: Add more key list safe checks

Signed-off-by: Gary Ching-Pang Lin <glin@suse.com>
MokManager: Support SHA224, SHA384, and SHA512

Signed-off-by: Gary Ching-Pang Lin <glin@suse.com>
MokManager: Discard the list contains an invalid signature

Signed-off-by: Gary Ching-Pang Lin <glin@suse.com>