UPSTREAM: media: v4l2-ctrl: Add control for h.264 chroma qp offset

Allow to add fixed quantization parameter offset between luma and
chroma quantization parameters. This control directly corresponds
to the chroma_qp_index_offset field of the h.264 picture parameter
set.

Bug: 161414994
Change-Id: Ie07c7719908331cf993c87aca2e9078db0019b34
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
(cherry picked from commit d034696cbe5a6e00f76ca4b7869c6cdef66aebd5)
Signed-off-by: Will McVicker <willmcvicker@google.com>