media: v4l2: Documentation for HEVC CIDs

Added V4L2 controls for HEVC encoder.

with V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN_10 to match the code.

[s.nawrocki@samsung.com]: Replaced V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN10
Signed-off-by: Smitha T Murthy <smitha.t@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>