media: staging: rkisp1: replace rkisp1_fmt_pix_type with v4l2_pixel_encoding

The enum rkisp1_fmt_pix_type that holds the pixel format
which is one of RGB, YUV, BAYER, can be replace by the
v4l2 enum v4l2_pixel_encoding.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>