ARM: gr8: Add UART3 pins

The UART3 pins were missing from the DTSI. Add them.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>

arch/arm/boot/dts/sun5i-gr8.dtsi

@@ -895,6 +895,20 @@ uart2_cts_rts_pins_a: uart2-cts-rts@0 {
 				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
 				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
 			};
+
+			uart3_pins_a: uart3@1 {
+				allwinner,pins = "PG9", "PG10";
+				allwinner,function = "uart3";
+				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
+				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
+			};
+
+			uart3_cts_rts_pins_a: uart3-cts-rts@0 {
+				allwinner,pins = "PG11", "PG12";
+				allwinner,function = "uart3";
+				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
+				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
+			};
 		};
 
 		pwm: pwm@01c20e00 {