media: staging: media: imx: imx7-media-csi: Ensure consistent function prefix

Rename all the functions and macros imported from imx-media-capture.c
with a consistent imx7_csi_video_ prefix. 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>