ARM: dts: imx6qdl-colibri: Add usdhc aliases

Add mmc aliases to ensure a consistent mmc device naming across the
Toradex SoM family, with this commit mmc0 is the on-module eMMC
boot device and the not available mmc interfaces are removed.
Signed-off-by: Hiago De Franco <hiago.franco@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/nxp/imx/imx6qdl-colibri.dtsi

@@ -12,6 +12,13 @@ / {
 	model = "Toradex Colibri iMX6DL/S Module";
 	compatible = "toradex,colibri_imx6dl", "fsl,imx6dl";
 
+	aliases {
+		mmc0 = &usdhc3; /* eMMC */
+		mmc1 = &usdhc1; /* MMC/SD Slot */
+		/delete-property/ mmc2;
+		/delete-property/ mmc3;
+	};
+
 	backlight: backlight {
 		compatible = "pwm-backlight";
 		brightness-levels = <0 45 63 88 119 158 203 255>;