Async I/O latency to a ssd greatly increased, 34% gain

(Creds: kleikamp)
Added optimized ARM RWSEM algorithm.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
mach-tegra: board-grouper-panel.c: change dithering mode