drm/sun4i: tcon: Support LVDS on the A33

The A33 TCON supports LVDS, so we can toggle the support switch.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200214120934.107924-1-maxime@cerno.tech