watchdog: imgpdc: Unregister restart handler on remove

Commit c631f20068 ("watchdog: imgpdc: Add reboot support") introduced
a restart handler but forgot to unregister it on driver removal. Fix it.

Fixes: c631f20068 ("watchdog: imgpdc: Add reboot support")
Reported-by: Ariel D'Alessandro <[e-mail]>
Signed-off-by: Ezequiel Garcia <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/imgpdc_wdt.c

···
 {
 	struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev);
 
+	unregister_restart_handler(&pdc_wdt->restart_handler);
 	pdc_wdt_stop(&pdc_wdt->wdt_dev);
 	watchdog_unregister_device(&pdc_wdt->wdt_dev);
 	clk_disable_unprepare(pdc_wdt->wdt_clk);