ARM: uniphier: enable CONFIG_MMC_HS400_SUPPORT for uniphier_v8_defconfig

The eMMC controller on LD20 or later supports HS-400 mode. It works on
a quick test. Enable it in case somebody may want to use it.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

configs/uniphier_v8_defconfig

@@ -39,7 +39,7 @@ CONFIG_I2C_EEPROM=y
 CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS=10
 CONFIG_SUPPORT_EMMC_RPMB=y
 CONFIG_SUPPORT_EMMC_BOOT=y
-CONFIG_MMC_HS200_SUPPORT=y
+CONFIG_MMC_HS400_SUPPORT=y
 CONFIG_MMC_UNIPHIER=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_ADMA=y