efi_loader: avoid make race condition

efi_loader: avoid make race condition

When U-Boot is built with 'make -j' there is not guarantee that targets in
directory arch/ are built before targets in directory lib/. The current
build instruction for EFI binaries in lib/ rely on dependencies in arch/.
If $(EFI_CRT0) or $(EFI_RELOC) is not yet built before trying to build
%.efi an error
    *** No rule to make target '%.efi'
occurs.

With the patch separate copies of $(EFI_CRT0) and $(EFI_RELOC) named
efi_crt0.o and efi_reloc.o are built in lib/efi_loader and
lib/efi_selftest.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>