[ARM] 3852/1: convert atomic bitops and __xchg over to raw_local_irq_{save,restore}

Thomas Gleixner noticed that bitops.h should also use the raw_* irq
disable/enable variants, and __xchg needs them as well.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>