Fix 'input rotationevent' sometimes not working issue

Observers exist for both Settings.System.USER_ROTATION and
Settings.System.ACCELEROMETER_ROTATION config values, and
updateSettings() may get wrong rotation status if these two values are
set separately. Use "mLock" to protect this situation and make sure they
are set together.

Change-Id: Ic89e6f14b45ee839c518e135096ae18d27f0a809
Signed-off-by: Carton He <carton.he@marvell.com>