Convert CONFIG_ARM_PL180_MMCI to Kconfig

This converts the following to Kconfig:
   CONFIG_ARM_PL180_MMCI

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/vexpress_ca9x4_defconfig b/configs/vexpress_ca9x4_defconfig
index 8234b5d..1811782 100644
--- a/configs/vexpress_ca9x4_defconfig
+++ b/configs/vexpress_ca9x4_defconfig
@@ -23,6 +23,7 @@
 CONFIG_CMD_UBI=y
 CONFIG_ENV_IS_IN_FLASH=y
 CONFIG_ENV_ADDR=0x47F80000
+CONFIG_ARM_PL180_MMCI=y
 CONFIG_MTD=y
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_FLASH_CFI_DRIVER=y