ARM: boolean bit testing

Bit testing (test, testset, testclear, testchange) for bit numbers
known at compile time returns a word with the tested-for bit set.

Change it to return a true boolean value so to make it consistent with
the out-of-line path and all the other bitops implementations.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>