media: v4l2-subdev: Allow accessing routes with STREAMS client capability

media: v4l2-subdev: Allow accessing routes with STREAMS client capability

Disable access to routes when the STREAMS client capability bit isn't set.
Routes aren't relevant otherwise anyway.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Mirela Rabulea <mirela.rabulea@nxp.com>
Reviewed-by: Michael Riesch <michael.riesch@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>