media: staging: media: imx: imx7-media-csi: Import imx_media_pipeline_set_stream()

To prepare for code refactoring, copy the
imx_media_pipeline_set_stream() helper used by this driver from
imx-media-utils.c. Rename the function to avoid name clashes, no
functional change intended.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Rui Miguel Silva <rmfrfs@gmail.com>
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>