auxdisplay: panel: need to delete scan_timer when misc_register fails in panel_attach

In panel_attach, if misc_register fails, we need to delete scan_timer,
which was setup in keypad_init->init_scan_timer.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

drivers/auxdisplay/panel.c

@@ -1617,6 +1617,8 @@ static void panel_attach(struct parport *port)
 	return;
 
 err_lcd_unreg:
+	if (scan_timer.function)
+		del_timer_sync(&scan_timer);
 	if (lcd.enabled)
 		charlcd_unregister(lcd.charlcd);
 err_unreg_device: