[efi] Add MNP headers from the UEFI 2.6 spec

Ideally this would be within gnu-efi, but the library appears to be
missing it along with a few other protocols. Long term it may make
sense to push this upstream, but for now I'm adding it local so it
can be used as-is.

Change-Id: If4f6d81a2a4bae131e2bfa146347849dba4132b8
1 file changed