ARM: dts: sun8i: add pinmux for UART1 at PG

The UART1 at PG (PG6, PG7, PG8, PG9) is, in the Allwinner's reference
tablet design of A23/33, used to connect to UART Bluetooth cards.

Add the pinmux for it.
Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun8i-a23-a33.dtsi

@@ -279,6 +279,16 @@ uart0_pins_a: uart0@0 {
 				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
 			};
 
+			uart1_pins_a: uart1@0 {
+				allwinner,pins = "PG6", "PG7";
+				allwinner,function = "uart1";
+			};
+
+			uart1_pins_cts_rts_a: uart1-cts-rts@0 {
+				allwinner,pins = "PG8", "PG9";
+				allwinner,function = "uart1";
+			};
+
 			mmc0_pins_a: mmc0@0 {
 				allwinner,pins = "PF0", "PF1", "PF2",
 						 "PF3", "PF4", "PF5";