pico-imx6ul: Convert to DM MMC

Select CONFIG_DM_MMC=y in order to support MMC driver model.

This allows the MMC board related code to be removed.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
diff --git a/arch/arm/mach-imx/mx6/Kconfig b/arch/arm/mach-imx/mx6/Kconfig
index d0cee51..e782859 100644
--- a/arch/arm/mach-imx/mx6/Kconfig
+++ b/arch/arm/mach-imx/mx6/Kconfig
@@ -403,7 +403,9 @@
 config TARGET_PICO_IMX6UL
 	bool "PICO-IMX6UL-EMMC"
 	select MX6UL
+	select DM
 	select SUPPORT_SPL
+	imply CMD_DM
 
 config TARGET_LITEBOARD
 	bool "Grinn liteBoard (i.MX6UL)"