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/Kconfig b/arch/Kconfig
index b0190b1..35b19f9 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -181,13 +181,13 @@
 	select DM_GPIO
 	select DM_I2C
 	select DM_KEYBOARD
-	select DM_MMC
 	select DM_SERIAL
 	select DM_SPI
 	select DM_SPI_FLASH
 	select GZIP_COMPRESSED
 	select IO_TRACE
 	select LZO
+	select MMC
 	select MTD
 	select OF_BOARD_SETUP
 	select PCI_ENDPOINT