usb: gadget: composite: fix delayed_status race condition when set_interface

It happens when enable debug log, if set_alt() returns
USB_GADGET_DELAYED_STATUS and usb_composite_setup_continue()
is called before increasing count of @delayed_status,
so fix it by using spinlock of @cdev->lock.
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Tested-by: Jay Hsu <shih-chieh.hsu@mediatek.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/composite.c

@@ -1719,6 +1719,8 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 		 */
 		if (w_value && !f->get_alt)
 			break;
+
+		spin_lock(&cdev->lock);
 		value = f->set_alt(f, w_index, w_value);
 		if (value == USB_GADGET_DELAYED_STATUS) {
 			DBG(cdev,
@@ -1728,6 +1730,7 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 			DBG(cdev, "delayed_status count %d\n",
 					cdev->delayed_status);
 		}
+		spin_unlock(&cdev->lock);
 		break;
 	case USB_REQ_GET_INTERFACE:
 		if (ctrl->bRequestType != (USB_DIR_IN|USB_RECIP_INTERFACE))