usb: gadget: udc: renesas_usb3: protect usb3_ep->started in usb3_start_pipen()

This patch fixes an issue that unexpected behavior happens when
both the interrupt handler and renesas_usb3_ep_enable() are called.
In this case, since usb3_start_pipen() checked the usb3_ep->started,
but the flags was not protected. So, this patch protects the flag
by usb3->lock. Since renesas_usb3_ep_enable() for EP0 will be not called,
this patch doesn't take care of usb3_start_pipe0().

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/renesas_usb3.c

@@ -1415,12 +1415,12 @@ static void usb3_start_pipen(struct renesas_usb3_ep *usb3_ep,
 	int ret = -EAGAIN;
 	u32 enable_bits = 0;
 
+	spin_lock_irqsave(&usb3->lock, flags);
 	if (usb3_ep->halt || usb3_ep->started)
-		return;
+		goto out;
 	if (usb3_req != usb3_req_first)
-		return;
+		goto out;
 
-	spin_lock_irqsave(&usb3->lock, flags);
 	if (usb3_pn_change(usb3, usb3_ep->num) < 0)
 		goto out;