arm: dts: sun8i: Add the TBS A711 tablet devicetree

The TBS A711 is a tablet with an A83T, a modem, wifi/BT chip, an eMMC and a
1024x600 LVDS display.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>