ARM: dts: imx6qdl: Add mmc aliases

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6qdl.dtsi

@@ -26,6 +26,10 @@ aliases {
 		i2c0 = &i2c1;
 		i2c1 = &i2c2;
 		i2c2 = &i2c3;
+		mmc0 = &usdhc1;
+		mmc1 = &usdhc2;
+		mmc2 = &usdhc3;
+		mmc3 = &usdhc4;
 		serial0 = &uart1;
 		serial1 = &uart2;
 		serial2 = &uart3;