[DRIVER MODEL] Add missing driver_unregister to IMX serial driver

Fix the IMX serial driver to unregister its driver structure
when it is unloaded.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/serial/imx.c

@@ -995,6 +995,7 @@ static int __init imx_serial_init(void)
 static void __exit imx_serial_exit(void)
 {
 	uart_unregister_driver(&imx_reg);
+	driver_unregister(&serial_imx_driver);
 }
 
 module_init(imx_serial_init);