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/M5272C3_defconfig b/configs/M5272C3_defconfig
index 9d86329..3d32a6f 100644
--- a/configs/M5272C3_defconfig
+++ b/configs/M5272C3_defconfig
@@ -27,3 +27,4 @@
 CONFIG_DM_ETH=y
 CONFIG_MCFFEC=y
 CONFIG_MII=y
+CONFIG_MCFUART=y