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/astro_mcf5373l_defconfig b/configs/astro_mcf5373l_defconfig
index 0878e7d..39910c5 100644
--- a/configs/astro_mcf5373l_defconfig
+++ b/configs/astro_mcf5373l_defconfig
@@ -37,3 +37,4 @@
 CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
 CONFIG_SYS_FLASH_PROTECTION=y
 CONFIG_SYS_FLASH_CFI=y
+CONFIG_MCFUART=y