usb: dwc3: ep0: clear all EP0 flags

when we're going to issue Set Stall command,
we should clear DWC3_EP_STALL flag, but also
we should clear BUSY, HALTED and all others.

Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 6745d14..618a29e 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -216,7 +216,7 @@
 {
 	/* stall is always issued on EP0 */
 	__dwc3_gadget_ep_set_halt(dwc->eps[0], 1);
-	dwc->eps[0]->flags &= ~DWC3_EP_STALL;
+	dwc->eps[0]->flags = DWC3_EP_ENABLED;
 	dwc->ep0state = EP0_SETUP_PHASE;
 	dwc3_ep0_out_start(dwc);
 }