usb: musb: gadget: nuke endpoint before setting its descriptor to NULL

Some functions, such as f_sourcesink, rely on an endpoint's desc
field during their requests' complete() callback, so clear it only
_after_ nuking all requests to avoid NULL pointer dereference.

Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_gadget.c

@@ -1164,12 +1164,12 @@ static int musb_gadget_disable(struct usb_ep *ep)
 		musb_writew(epio, MUSB_RXMAXP, 0);
 	}
 
-	musb_ep->desc = NULL;
-	musb_ep->end_point.desc = NULL;
-
 	/* abort all pending DMA and requests */
 	nuke(musb_ep, -ESHUTDOWN);
 
+	musb_ep->desc = NULL;
+	musb_ep->end_point.desc = NULL;
+
 	schedule_work(&musb->irq_work);
 
 	spin_unlock_irqrestore(&(musb->lock), flags);