provide arch_test_bit_acquire for architectures that define test_bit

Some architectures define their own arch_test_bit and they also need
arch_test_bit_acquire, otherwise they won't compile.  We also clean up
the code by using the generic test_bit if that is equivalent to the
arch-specific version.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 8238b457 ("wait_on_bit: add an acquire memory barrier")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>