[media] docs-rst: fix warnings introduced by LaTeX patchset

[media] docs-rst: fix warnings introduced by LaTeX patchset

Sphinx is really pedantic with respect to the order where
table tags and references are created. Putting things at
the wrong order causes troubles.

The order that seems to work is:

	.. raw:: latex

	.. tabularcolumns::

	.. _foo_name:

	.. cssclass: longtable

	.. flat-table::

Reorder the tags to the above order, to avoid troubles, and
fix remaining warnings introduced by media recent patches.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>