efi_loader: add helper macro to construct protocol objects

efi_loader: add helper macro to construct protocol objects

There are a bunch of protocols which should be exposed by GUID but are
not.  Add a helper macro to create an efi_object, to avoid much typing.

Note that using the pointer for efiobj->handle is semi-arbitrary.  We
just need a unique value to match the efiobj supporting the protocol
with the handle that LocateHandle() returns..

See LibLocateProtocol() in gnu-efi.  It does LocateHandle() to find all
the handles, and then loops over them calling HandleProtocol() with the
GUID of the protocol it is trying to find.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>