x86/efi: Split the boot stub into 32/64 code paths
x86/efi: Split the boot stub into 32/64 code paths

Make the decision which code path to take at runtime based on
efi_early->is64.

Signed-off-by: Matt Fleming <b02f0790d66a0f0a6b369873bf6df37420fbe5dd@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs