arm: sunxi: Enable DM_MMC

Enable DM_MMC for all Allwinner SoCs, this will eventually
enable BLK.

Also removed DM_MMC enablement in few parts of sunxi
configurations.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index cefa8f4..f0edb10 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -851,6 +851,7 @@
 	select DM_ETH
 	select DM_GPIO
 	select DM_KEYBOARD
+	select DM_MMC if MMC
 	select DM_SERIAL
 	select DM_USB if DISTRO_DEFAULTS
 	select OF_BOARD_SETUP