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>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 807737a..b84418e 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1925,7 +1925,7 @@
 
 	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);