dt-bindings: display: Add compatible for A64 HDMI

dt-bindings: display: Add compatible for A64 HDMI

The HDMI controller on Allwinner A64 is similar on the one on
H3/H5/A83T (although the PHY is different with A83T).

Add A64 compatible and append A83T compatible as fallback.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Rob Herring <robh@kernel.org>
[Icenowy: refactor commit log]
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180904044053.15425-7-icenowy@aosc.io