media: docs: v4l2-controls: fix sentence rendered in a nonsense way

This sentence renders as:

> Since such compound controls need to expose more information about
> themselves than is possible with ioctls VIDIOC_QUERYCTRL,
> VIDIOC_QUERY_EXT_CTRL and VIDIOC_QUERYMENU the VIDIOC_QUERY_EXT_CTRL
  ^^^^^^^^^^^^^^^^^^^^^                          ^^^^^^^^^^^^^^^^^^^^^
> ioctl was added.

This does not make sense. Fix by providing an explicit link text. This
results in:

> Since such compound controls need to expose more information about
> themselves than is possible with VIDIOC_QUERYCTRL the
> VIDIOC_QUERY_EXT_CTRL ioctl was added.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/extended-controls.rst

@@ -85,11 +85,10 @@ be able to see such compound controls. In other words, these controls
 with compound types should only be used programmatically.
 
 Since such compound controls need to expose more information about
-themselves than is possible with
-:ref:`VIDIOC_QUERYCTRL` the
-:ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>` ioctl was added. In
-particular, this ioctl gives the dimensions of the N-dimensional array
-if this control consists of more than one element.
+themselves than is possible with :ref:`VIDIOC_QUERYCTRL <VIDIOC_QUERYCTRL>`
+the :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>` ioctl was added. In
+particular, this ioctl gives the dimensions of the N-dimensional array if
+this control consists of more than one element.
 
 .. note::