colibri_imx6: migrate mmc to using driver model

Migrate MMC to using driver model.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
diff --git a/configs/colibri_imx6_defconfig b/configs/colibri_imx6_defconfig
index 6fd050a..2ab7db4 100644
--- a/configs/colibri_imx6_defconfig
+++ b/configs/colibri_imx6_defconfig
@@ -54,6 +54,7 @@
 CONFIG_DFU_MMC=y
 CONFIG_DM_GPIO=y
 CONFIG_DM_I2C=y
+CONFIG_DM_MMC=y
 CONFIG_FSL_ESDHC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y