mips: lock bitops

mips can avoid one mb when acquiring a lock with test_and_set_bit_lock.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>