x86/EFI: sanitize build logic
With changes done over time and as far as linking goes, the only special
thing about building with EFI support enabled is the need for the dummy
relocations object for xen.gz uniformly in all build stages. All other
efi/*.o can be consumed from the built_in*.o files.
In efi/Makefile, besides moving relocs-dummy.o to "extra", also properly
split between obj-y and obj-bin-y.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>