UPSTREAM: media: docs: Document CLL and Mastering display colorimetry controls

Document Content Light Level and Mastering Display v4l2 colorimetry
controls.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
(cherry picked from commit 5f8beb7d)
BUG: 175389589

Change-Id: I4b262af9464ee3d9f11eb0bfc3fdc372ab2a1e18
Signed-off-by: Dikshita Agarwal <dikshita@codeaurora.org>