Optimized ARM RWSEM algorithm
RWSEM implementation for ARM using atomic functions.

Heavily based on arch/sh/include/asm/rwsem.h

Signed-off-by: Ashwin Chaugule <ashwinc@codeaurora.org>
(cherry picked from commit 565715b)

Signed-off-by: nobodyAtall <tsogkas@ceid.upatras.gr>