media: max96712: Depend on VIDEO_V4L2

Depend on VIDEO_V4L2 for the driver actually depends on it, failing to
compile otherwise.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>