media: camss: use proper media entity function for subdevices

Currently for msm_csiphy, msm_csid, and msm_ispif subdevices the media
entity function field is set to MEDIA_ENT_F_IO_V4L. This is incorrect
as MEDIA_ENT_F_IO_V4L implies V4L2 video node.

Change it to MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER as this is the best
fit from the functions defined in include/uapi/linux/media.h.

Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Tested-by: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>