ARM: dts: sun8i: V3/V3s/S3/S3L: add pinctrl for UART2 RX/TX

The UART2 RX/TX pins on Allwinner V3 series is at PB0/1, which is used
as debugging UART on some boards.

Add pinctrl node for them.
Signed-off-by: NIcenowy Zheng <icenowy@aosc.io>
Signed-off-by: NMaxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20200923005858.148261-1-icenowy@aosc.io

arch/arm/boot/dts/sun8i-v3s.dtsi

@@ -322,6 +322,11 @@
 				function = "uart0";
 			};
 
+			uart2_pins: uart2-pins {
+				pins = "PB0", "PB1";
+				function = "uart2";
+			};
+
 			mmc0_pins: mmc0-pins {
 				pins = "PF0", "PF1", "PF2", "PF3",
 				       "PF4", "PF5";
@@ -397,6 +402,8 @@
 			reg-io-width = <4>;
 			clocks = <&ccu CLK_BUS_UART2>;
 			resets = <&ccu RST_BUS_UART2>;
+			pinctrl-0 = <&uart2_pins>;
+			pinctrl-names = "default";
 			status = "disabled";
 		};