ARM: dts: imx7-mba7: update MMC aliases

Together with the recently merged support for alias-based MMC host
numbering, this makes the MMC devices names match what the bootloader
expects.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7-mba7.dtsi

@@ -14,6 +14,12 @@
 #include <dt-bindings/net/ti-dp83867.h>
 
 / {
+	aliases {
+		mmc0 = &usdhc3;
+		mmc1 = &usdhc1;
+		/delete-property/ mmc2;
+	};
+
 	beeper {
 		compatible = "gpio-beeper";
 		gpios = <&pca9555 0 GPIO_ACTIVE_HIGH>;