ARM: dts: sun8i: r40: Add HDMI pipeline

Add all entries needed for HDMI to function properly.

Since R40 has highly configurable pipeline, both mixers and both TCON
TVs are added. Board specific DT should then connect them together
trough TCON TOP muxers to best fit the purpose of the board.

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