usb: dwc3: gadget: fix set_halt() bug with pending transfers

commit 7a60855972f0d3c014093046cb6f013a1ee5bb19 upstream.

According to our Gadget Framework API documentation,
->set_halt() *must* return -EAGAIN if we have pending
transfers (on either direction) or FIFO isn't empty (on
TX endpoints).

Fix this bug so that the mass storage gadget can be used
without stall=0 parameter.

This patch should be backported to all kernels since v3.2.

Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@ti.com>
[lizf: Backported to 3.4:
 - adjust context
 - drop the change to dwc3_gadget_ep_set_wedge()]
Signed-off-by: Zefan Li <lizefan@huawei.com>
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 5bf2bc0..8a7a8ee 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -209,7 +209,7 @@
 	struct dwc3_ep		*dep = dwc->eps[0];
 
 	/* stall is always issued on EP0 */
-	__dwc3_gadget_ep_set_halt(dep, 1);
+	__dwc3_gadget_ep_set_halt(dep, 1, false);
 	dep->flags = DWC3_EP_ENABLED;
 	dwc->delayed_status = false;
 
@@ -382,7 +382,7 @@
 				return -EINVAL;
 			if (set == 0 && (dep->flags & DWC3_EP_WEDGE))
 				break;
-			ret = __dwc3_gadget_ep_set_halt(dep, set);
+			ret = __dwc3_gadget_ep_set_halt(dep, set, true);
 			if (ret)
 				return -EINVAL;
 			break;