usb: dwc3: clean TRB if STARTTRANSFER fail

In case STARTTRANSFER will fail, clean TRB.
Seems HW in such case don't clean HWO bit.
So, without this cleanup prev_trb still have
HWO bit set.

In my case (without patch), after first START failed:
- dep->enqueue == 1
- dep->dequeue == 1
- prev_trb still have HWO set
- left_trb() == 0
No way to send more data.
Signed-off-by: Janusz Dziedzic <januszx.dziedzic@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/gadget.c

@@ -1084,6 +1084,8 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, u16 cmd_param)
 		 * here and stop, unmap, free and del each of the linked
 		 * requests instead of what we do now.
 		 */
+		if (req->trb)
+			memset(req->trb, 0, sizeof(struct dwc3_trb));
 		dep->queued_requests--;
 		dwc3_gadget_giveback(dep, req, ret);
 		return ret;