ARM: dts: sun7i: Add SPDIF TX pin to the A20

Add the SPDIF TX pin to the A20 dtsi.
Signed-off-by: Marcus Cooper <codekipper@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun7i-a20.dtsi

@@ -1193,6 +1193,13 @@ ps21_pins_a: ps21@0 {
 				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
 				allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
 			};
+
+			spdif_tx_pins_a: spdif@0 {
+				allwinner,pins = "PB13";
+				allwinner,function = "spdif";
+				allwinner,drive = <SUN4I_PINCTRL_10_MA>;
+				allwinner,pull = <SUN4I_PINCTRL_PULL_UP>;
+			};
 		};
 
 		timer@01c20c00 {