arm64: allwinner: h6: add support for Pine H64 board

Pine H64 is an Allwinner H6-based SBC from Pine64, with the following
features:

- 1GiB/2GiB/4GiB LPDDR3 DRAM (in 4GiB situation only 3GiB is
accessible)
- AXP805 PMIC
- Raspberry-Pi-compatible GPIO header, "Euler" GPIO header (not
compatible with the "Euler" on Pine A64) and "Expansion" pin header
- 2 USB 2.0 ports and 1 USB 3.0 ports
- Audio jack
- MicroSD slot and eMMC module slot
- on-board SPI NOR flash
- 1Gbps Ethernet port (via RTL8211E PHY)
- HDMI port

Adds initial support for it, including the UART on the Expansion pin
header.
Signed-off-by: NIcenowy Zheng <icenowy@aosc.io>
Reviewed-by: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>

arch/arm64/boot/dts/allwinner/Makefile

@@ -10,3 +10,4 @@ dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h5-orangepi-prime.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h5-orangepi-zero-plus2.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h5-nanopi-neo2.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h5-nanopi-neo-plus2.dtb
+dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h6-pine-h64.dtb

arch/arm64/boot/dts/allwinner/sun50i-h6-pine-h64.dts

+// SPDX-License-Identifier: (GPL-2.0+ or MIT)
+/*
+ * Copyright (c) 2017 Icenowy Zheng <icenowy@aosc.io>
+ */
+
+/dts-v1/;
+
+#include "sun50i-h6.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+	model = "Pine H64";
+	compatible = "pine64,pine-h64", "allwinner,sun50i-h6";
+
+	aliases {
+		serial0 = &uart0;
+	};
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+};
+
+&uart0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&uart0_ph_pins>;
+	status = "okay";
+};