msm: sde: Protect concurrent access to resources in SDE rotator

ioctl32 handling in SDE rotator does not go through the V4L2 ioctl
lock protection, thus allowing concurrent access to some of the SDE
rotator internal resources. This change adds the mutex protection to
the SDE rotator ioctl32 handler.

CRs-Fixed: 2019300
Change-Id: Idca37e19b7d3812e90d143acfc6fef82df19ab97
Signed-off-by: Benjamin Chan <bkchan@codeaurora.org>