USB: EHCI: Rearrange EHCI_URB_TRACE code to avoid GCC-4.6 warnings.

With pre-release GCC-4.6, we get a 'set but not used' warning when
EHCI_URB_TRACE is not set because we set the qtd variable without
using it.

Rearrange the statements so that we only set qtd if it will be used.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ehci-q.c

@@ -1107,22 +1107,24 @@ submit_async (
 	struct list_head	*qtd_list,
 	gfp_t			mem_flags
 ) {
-	struct ehci_qtd		*qtd;
 	int			epnum;
 	unsigned long		flags;
 	struct ehci_qh		*qh = NULL;
 	int			rc;
 
-	qtd = list_entry (qtd_list->next, struct ehci_qtd, qtd_list);
 	epnum = urb->ep->desc.bEndpointAddress;
 
 #ifdef EHCI_URB_TRACE
-	ehci_dbg (ehci,
-		"%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
-		__func__, urb->dev->devpath, urb,
-		epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
-		urb->transfer_buffer_length,
-		qtd, urb->ep->hcpriv);
+	{
+		struct ehci_qtd *qtd;
+		qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
+		ehci_dbg(ehci,
+			 "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
+			 __func__, urb->dev->devpath, urb,
+			 epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
+			 urb->transfer_buffer_length,
+			 qtd, urb->ep->hcpriv);
+	}
 #endif
 
 	spin_lock_irqsave (&ehci->lock, flags);