doc-rst: linux_tv: remove whitespaces

Let's remove bad whitespaces on the entire book.

That helps to avoid mixing whitespace removal with other
patches.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/linux_tv/media/v4l/userp.rst

@@ -76,7 +76,7 @@ started. In the write loop, when the application runs out of free
 buffers it must wait until an empty buffer can be dequeued and reused.
 Two methods exist to suspend execution of the application until one or
 more buffers can be dequeued. By default :ref:`VIDIOC_DQBUF
-<VIDIOC_QBUF>`` blocks when no buffer is in the outgoing queue. When the
+<VIDIOC_QBUF>` blocks when no buffer is in the outgoing queue. When the
 ``O_NONBLOCK`` flag was given to the :ref:`open() <func-open>` function,
 :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` returns immediately with an ``EAGAIN``
 error code when no buffer is available. The :ref:`select()