ARM: dts: sun8i: a83t: Add HDMI display pipeline

This commit adds all bits necessary for HDMI on A83T - mixer1, tcon1,
hdmi, hdmi phy and hdmi pinctrl entries.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>