dts: sun8i-h3: add pinmux definitions for UART2-3

These are the pinmux definitions for UART2-3 on H3. These UARTs can only
be muxed to these pins, so _a and @0 do not really make sense. I have
left out RTS/CTS, since these are rarely used. These can easily be
enabled using an additional pinmux set.
Signed-off-by: Jorik Jonker <jorik@kippendief.biz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun8i-h3.dtsi

@@ -373,6 +373,20 @@ uart1_pins_a: uart1@0 {
 				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
 				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
 			};
+
+			uart2_pins: uart2 {
+				allwinner,pins = "PA0", "PA1";
+				allwinner,function = "uart2";
+				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
+				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
+			};
+
+			uart3_pins: uart3 {
+				allwinner,pins = "PG13", "PG14";
+				allwinner,function = "uart3";
+				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
+				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
+			};
 		};
 
 		timer@01c20c00 {