[media] tc358743: enable v4l2 subdevice devnode

Add V4L2_SUBDEV_FL_HAS_DEVNODE to subdev flags, in order to
enable a subdev device node.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>