drm/sun4i: tv: Convert to the new TV mode property

Now that the core can deal fine with analog TV modes, let's convert the
sun4i TV driver to leverage those new features.

Acked-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-in-principle-or-something-like-that-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-19-256dad125326@cerno.tech


Signed-off-by: Maxime Ripard <maxime@cerno.tech>