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/configs/uniphier_sld3_defconfig b/configs/uniphier_sld3_defconfig
index 013fc8a..5f0d678 100644
--- a/configs/uniphier_sld3_defconfig
+++ b/configs/uniphier_sld3_defconfig
@@ -18,6 +18,7 @@
 # CONFIG_CMD_MISC is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_GPIO_UNIPHIER=y
+CONFIG_MMC_UNIPHIER=y
 CONFIG_NAND_DENALI=y
 CONFIG_SYS_NAND_DENALI_64BIT=y
 CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES=8