media: v4l2-subdev: Fix missing kerneldoc for client_caps

Add missing kernel doc for the new 'client_caps' field in struct
v4l2_subdev_fh.

Signed-off-by: Tomi Valkeinen <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Fixes: f57fa2959244 ("media: v4l2-subdev: Add new ioctl for client capabilities")
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

include/media/v4l2-subdev.h

···
  * @vfh: pointer to &struct v4l2_fh
  * @state: pointer to &struct v4l2_subdev_state
  * @owner: module pointer to the owner of this file handle
+ * @client_caps: bitmask of ``V4L2_SUBDEV_CLIENT_CAP_*``
  */
 struct v4l2_subdev_fh {
 	struct v4l2_fh vfh;