arm64: allwinner: dts: a64: add DT for Early Adopter's PineTab

PineTabs since Early Adopter batch will use a new LCD panel.

Add device tree for PineTab with the new panel.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20201224024001.19248-2-icenowy@aosc.io