usb: dwc3: calculate number of event buffers dynamically

This will allow us to only allocate memory when
we actually need.

Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/gadget.c

@@ -1925,7 +1925,7 @@ static irqreturn_t dwc3_interrupt(int irq, void *_dwc)
 
 	spin_lock(&dwc->lock);
 
-	for (i = 0; i < DWC3_EVENT_BUFFERS_NUM; i++) {
+	for (i = 0; i < dwc->num_event_buffers; i++) {
 		irqreturn_t status;
 
 		status = dwc3_process_event_buf(dwc, i);