media: staging: media: imx: imx7-media-csi: Import format helpers

To prepare for code refactoring, copy the format helpers used by this
driver from imx-media-utils.c. Rename structures and functions 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>