x86/EFI: Properly init-annotate BGRT code

These items are only ever referenced from initialization code.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: <mjg@redhat.com>
Link: http://lkml.kernel.org/r/50AFB29F02000078000AAE8E@nat28.tlf.novell.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>