ARM: uniphier: enable UniPhier SD/MMC host driver

Enable the driver in all UniPhier defconfig files and add some
needed defines to the common files.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 94bd7ec..37b20ff 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -700,6 +700,7 @@
 	select DM_GPIO
 	select DM_SERIAL
 	select DM_I2C
+	select DM_MMC
 	help
 	  Support for UniPhier SoC family developed by Socionext Inc.
 	  (formerly, System LSI Business Division of Panasonic Corporation)