media: imx: Drop manual dependency on VIDEO_IMX_MEDIA

The VIDEO_IMX_CSI and VIDEO_IMX7_CSI symbols are defined in a section
guarded by VIDEO_IMX_MEDIA. There's no need to duplicate that with a
"depends on" statement. Drop it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>