ARM: dts: sun8i: V3/S3: Add UART1 pin definitions to the V3/S3 dtsi

The Allwinner V3 and S3 can use PG6/7 as RX/TX for UART1. Since no other
functions are assigned to those pins, they are a convenient choice for
a debugging or application UART.
This is specific to V3/S3 as the V3s's non-BGA package did not have
those pins.

Signed-off-by: Matteo Scordino <[e-mail]>
Signed-off-by: Maxime Ripard <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/arm/boot/dts/sun8i-v3.dtsi

···
 
 &pio {
 	compatible = "allwinner,sun8i-v3-pinctrl";
+
+	uart1_pg_pins: uart1-pg-pins {
+		pins = "PG6", "PG7";
+		function = "uart1";
+	};
 };