arm64: dts: allwinner: a64: Orange Pi Win: Add UARTs

The Orange Pi Win exposes several UARTs on header pins, and connects one
to the on-board WiFi/Bluetooth chip.

Add the pinmux definitions to the UART nodes, but keep them disabled.
Enable the UART1, which is wired to the Bluetooth chip, and add a serdev
node. There is no binding for the BT8723 yet, so leave this mostly empty
for now.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>