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 <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/mcf.c

···
 	if (rc)
 		return rc;
 	rc = platform_driver_register(&mcf_platform_driver);
-	if (rc)
+	if (rc) {
+		uart_unregister_driver(&mcf_driver);
 		return rc;
+	}
 	return 0;
 }