serial: mcf: missing uart_unregister_driver() on error in mcf_init()

Add the missing uart_unregister_driver() before return
from mcf_init() in the error handling case.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mcf.c

@@ -707,8 +707,10 @@ static int __init mcf_init(void)
 	if (rc)
 		return rc;
 	rc = platform_driver_register(&mcf_platform_driver);
-	if (rc)
+	if (rc) {
+		uart_unregister_driver(&mcf_driver);
 		return rc;
+	}
 	return 0;
 }