ARM64: dts: meson-gx: add the missing uart_AO_B

This adds the missing node for the uart_AO_B port to the meson-gx.dtsi
(as this is supported by GXBB, GXL and GXM) along with the required
pinctrl pins. This is required as some boards are using it (the boards
from the Khadas VIM series for example have it exposed on the pin
headers).
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

arch/arm64/boot/dts/amlogic/meson-gx.dtsi

@@ -324,6 +324,14 @@ uart_AO: serial@4c0 {
 				status = "disabled";
 			};
 
+			uart_AO_B: serial@4e0 {
+				compatible = "amlogic,meson-uart";
+				reg = <0x0 0x004e0 0x0 0x14>;
+				interrupts = <GIC_SPI 197 IRQ_TYPE_EDGE_RISING>;
+				clocks = <&xtal>;
+				status = "disabled";
+			};
+
 			ir: ir@580 {
 				compatible = "amlogic,meson-gxbb-ir";
 				reg = <0x0 0x00580 0x0 0x40>;

arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi

@@ -138,6 +138,13 @@ mux {
 			};
 		};
 
+		uart_ao_b_pins: uart_ao_b {
+			mux {
+				groups = "uart_tx_ao_b", "uart_rx_ao_b";
+				function = "uart_ao_b";
+			};
+		};
+
 		remote_input_ao_pins: remote_input_ao {
 			mux {
 				groups = "remote_input_ao";

arch/arm64/boot/dts/amlogic/meson-gxl.dtsi

@@ -88,6 +88,13 @@ mux {
 			};
 		};
 
+		uart_ao_b_pins: uart_ao_b {
+			mux {
+				groups = "uart_tx_ao_b", "uart_rx_ao_b";
+				function = "uart_ao_b";
+			};
+		};
+
 		remote_input_ao_pins: remote_input_ao {
 			mux {
 				groups = "remote_input_ao";