ARM: dts: sun6i: Add pin-muxing info for the mmc controllers

This adds  pin-muxing info for the mmc controller / port combinations which
are known to be used on actual boards.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun6i-a31.dtsi

@@ -295,6 +295,13 @@ i2c2_pins_a: i2c2@0 {
 				allwinner,drive = <0>;
 				allwinner,pull = <0>;
 			};
+
+			mmc0_pins_a: mmc0@0 {
+				allwinner,pins = "PF0","PF1","PF2","PF3","PF4","PF5";
+				allwinner,function = "mmc0";
+				allwinner,drive = <2>;
+				allwinner,pull = <0>;
+			};
 		};
 
 		ahb1_rst: reset@01c202c0 {