ARM: dts: imx6dl: add alias for I2C4 bus

On registration I2C bus drivers attemp to get ids from device tree
aliases, add a missing alias for I2C4 found on iMX6 DualLite/Solo.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6dl.dtsi

@@ -13,6 +13,10 @@
 #include "imx6qdl.dtsi"
 
 / {
+	aliases {
+		i2c3 = &i2c4;
+	};
+
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;