Revert "usb: dwc3: gadget: remove unnecessary _irqsave()"

static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc)

{

	struct dwc3 *dwc = _dwc;

	unsigned long flags;

	irqreturn_t ret = IRQ_NONE;

	int i;

	spin_lock(&dwc->lock);

	spin_lock_irqsave(&dwc->lock, flags);

	for (i = 0; i < dwc->num_event_buffers; i++)

		ret |= dwc3_process_event_buf(dwc, i);

	spin_unlock(&dwc->lock);

	spin_unlock_irqrestore(&dwc->lock, flags);

	return ret;

}