Convert CONFIG_MCFUART to Kconfig

This converts the following to Kconfig:
	CONFIG_MCFUART

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/stmark2_defconfig b/configs/stmark2_defconfig
index eb6d5a7..e7b68cd 100644
--- a/configs/stmark2_defconfig
+++ b/configs/stmark2_defconfig
@@ -36,6 +36,7 @@
 CONFIG_SF_DEFAULT_SPEED=50000000
 CONFIG_SPI_FLASH_ISSI=y
 CONFIG_SPI_FLASH_MTD=y
+CONFIG_MCFUART=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_CF_SPI=y