media: v4l2-subdev: Fail {enable,disable}_streams and s_streaming nicely

media: v4l2-subdev: Fail {enable,disable}_streams and s_streaming nicely

If a sub-device does not set enable_streams() and disable_streams() pad
ops while it sets the s_stream() video op to
v4l2_subdev_s_stream_helper(), enabling or disabling streaming either way
on the sub-device will result calling v4l2_subdev_s_stream_helper() and
v4l2_subdev_{enable,disable}_streams() recursively, exhausting the stack.
Return -ENOIOCTLCMD in this case to handle the situation gracefully.

Fixes: b62949ddaa52 ("media: subdev: Support single-stream case in v4l2_subdev_enable/disable_streams()")
Cc: stable@vger.kernel.org
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>