Add following V4L2 QP parameters for H.264:
* V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP
* V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP
* V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP
* V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP

These controls will limit QP range for intra and inter frame,
provide more manual control to improve video encode quality.
Signed-off-by: Fish Lin <linfish@google.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>