usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()

There is more possibility for sharing code if we just realise that now
__dwc3_gadget_kic_transfer() knows to break out early if there are no
TRBs left.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/gadget.c

@@ -1290,7 +1290,6 @@ static void dwc3_gadget_start_isoc(struct dwc3 *dwc,
 static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 {
 	struct dwc3		*dwc = dep->dwc;
-	int			ret = 0;
 
 	if (!dep->endpoint.desc) {
 		dev_err(dwc->dev, "%s: can't queue to disabled endpoint\n",
@@ -1337,24 +1336,14 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 		}
 
 		if ((dep->flags & DWC3_EP_BUSY) &&
-		    !(dep->flags & DWC3_EP_MISSED_ISOC)) {
-			WARN_ON_ONCE(!dep->resource_index);
-			ret = __dwc3_gadget_kick_transfer(dep,
-							  dep->resource_index);
-		}
-
+		    !(dep->flags & DWC3_EP_MISSED_ISOC))
 			goto out;
-	}
 
-	if (!dwc3_calc_trbs_left(dep))
 		return 0;
+	}
 
-	ret = __dwc3_gadget_kick_transfer(dep, 0);
 out:
-	if (ret == -EBUSY)
-		ret = 0;
-
-	return ret;
+	return __dwc3_gadget_kick_transfer(dep, 0);
 }
 
 static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,