ARM: dts: sun7i: cubietruck: set mmc3 bus-width property

bus-width defaults to 1, and all 4 lines are hooked up at the cubietruck,
properly set bus-width to 4.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

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

@@ -34,6 +34,7 @@
 			pinctrl-names = "default";
 			pinctrl-0 = <&mmc3_pins_a>;
 			vmmc-supply = <&reg_vmmc3>;
+			bus-width = <4>;
 			non-removable;
 			status = "okay";
 		};