media: msm_vidc: add v4l2 controls for video encoder

Adds encoder specific v4l2 controls in video driver, giving
flexibility to userspace or in-kernel v4l2 client to change/set
video encoder properties like  codec, profile, level, resolution,
bitrate, ratecontrol, framerate to video hardware.

Change-Id: Ie9d0eed301c3adad20471d8ef93f8087fe9dda15
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>