arm64: dts: allwinner: a64: add HDMI regulator to all DTs' simplefb_hdmi

On usual A64 board design the power of HDMI controller is connected to
DLDO1 of the AXP803 PMIC. If this regulator is shut down, the HDMI
output will be blank. Therefore the simplefb driver should keep this
regulator on.

Add the regulator to all currently available A64 boards' simplefb_hdmi
device node, if the board is capable of outputing HDMI.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>