drivers/mmc/Kconfig: Make DM_MMC a hidden symbol

At this point in time, DM is always enabled. So if MMC is enabled, it
should select DM_MMC. No drivers need to depend on DM_MMC being enabled
now, so remove that from dependency lists. This now means that a number
of platforms which select'd DM_MMC need to select MMC instead. This also
fixes a migration problem with espresso7420 in that MMC is built again
with the platform.

Reviewed-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-imx/mx5/Kconfig b/arch/arm/mach-imx/mx5/Kconfig
index d282663..4d1e07b 100644
--- a/arch/arm/mach-imx/mx5/Kconfig
+++ b/arch/arm/mach-imx/mx5/Kconfig
@@ -26,9 +26,9 @@
 	select DM_I2C
 	select DM_PMIC
 	select DM_SERIAL
-	select DM_MMC
 	select BLK
 	select DM_REGULATOR
+	select MMC
 	select MX53
 	imply CMD_DM