msm: mdss: Exempt PP related ioctls from FB ioctl wait idle

The postprocessing related ioctls should not block to wait for fb_pan_idle.
They are not dependent on display commits completing.
Add PP and histogram ioctls to the list of commands that don't have
to wait for pan_idle.

Change-Id: Ie5110bc6b64761520d9a182f7ec21b4830815326
Signed-off-by: Siva Yarravarapu <sivay@codeaurora.org>