Fix memmove-vec-unaligned-erms.S

__mempcpy_erms and __memmove_erms can't be placed between __memmove_chk
and __memmove it breaks __memmove_chk.

Don't check source == destination first since it is less common.

	* sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:
	(__mempcpy_erms, __memmove_erms): Moved before __mempcpy_chk
	with unaligned_erms.
	(__memmove_erms): Skip if source == destination.
	(__memmove_unaligned_erms): Don't check source == destination
	first.