media: staging: media: imx: imx7-media-csi: Remove imx_media_of_add_csi

imx_media_of_add_csi() from imx-media-of.c validates that the fwnode for
the CSI bridge is enabled, and adds the fwnode to the async notifier of
the imxmd. The former is redundant, as if the CSI bridge driver probes,
clearly it is enabled in the DT. The latter is not needed as the imxmd
notifier isn't used anymore. The call is thus not needed and can be
dropped. This removes the dependency of imx7-media-csi.c on
imx-media-of.c.

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