imx: Fix regression with CONFIG_DM_MMC=y

When CONFIG_DM_MMC=y, CONFIG_BLK should be selected, otherwise the
SD/eMMC card cannot be used.

Also, select CONFIG_DM_USB=y when CONFIG_USB=y to avoid build failure.

Tested on mx6slevk, mx7dsabresd and mx6ullevk.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Tested-by: Adam Ford <aford173@gmail.com>
Tested-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Tested-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/configs/mx6sxsabreauto_defconfig b/configs/mx6sxsabreauto_defconfig
index ca8453b..5ef95d1 100644
--- a/configs/mx6sxsabreauto_defconfig
+++ b/configs/mx6sxsabreauto_defconfig
@@ -28,7 +28,6 @@
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
 CONFIG_OF_CONTROL=y
-# CONFIG_BLK is not set
 CONFIG_DM_GPIO=y
 CONFIG_DM_PCA953X=y
 CONFIG_DM_I2C=y
@@ -47,6 +46,7 @@
 CONFIG_DM_REGULATOR_GPIO=y
 CONFIG_FSL_QSPI=y
 CONFIG_USB=y
+CONFIG_DM_USB=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_ASIX=y