[media] v4l2-ioctl.h add debug info for struct v4l2_ioctl_ops

This struct is mentioned at the kAPI docbook. So, let's document
it.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/kapi/v4l2-common.rst

@@ -2,3 +2,5 @@ V4L2 common functions and data structures
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 .. kernel-doc:: include/media/v4l2-common.h
+
+.. kernel-doc:: include/media/v4l2-ioctl.h