ARM: embestmx6boards: convert the mars/riot boards to DM_MMC

Convert the two Embest boards to use DM MMC.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Cc: "Eric BĂ©nard" <eric@eukrea.com>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/dts/imx6dl-riotboard-u-boot.dtsi b/arch/arm/dts/imx6dl-riotboard-u-boot.dtsi
new file mode 100644
index 0000000..e51cd24
--- /dev/null
+++ b/arch/arm/dts/imx6dl-riotboard-u-boot.dtsi
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/ {
+	aliases {
+		mmc0 = &usdhc2;
+		mmc1 = &usdhc3;
+	};
+};
diff --git a/arch/arm/dts/imx6q-marsboard-u-boot.dtsi b/arch/arm/dts/imx6q-marsboard-u-boot.dtsi
new file mode 100644
index 0000000..e51cd24
--- /dev/null
+++ b/arch/arm/dts/imx6q-marsboard-u-boot.dtsi
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/ {
+	aliases {
+		mmc0 = &usdhc2;
+		mmc1 = &usdhc3;
+	};
+};