media: v4l2: add video controls in v4l2 framework.

Adds control definitions in v4l2 framework needed for
configuring video codec properties. Userspace clients
and in-kernel clients can make calls into video driver
to set/change codec properties like codec, profile, level,
resolution, bitrate, ratecontrol, framerate.

Change-Id: I6396106af69b2686a78b83d5833cd60a1c6d4cef
[davidb: only drivers/media/video/v4l2-ctrls.c]
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>