xhci: fix finding correct bus_state structure for USB 3.1 hosts

xhci driver keeps a bus_state structure for each hcd (usb2 and usb3)

The structure is picked based on hcd speed, but driver only compared
for HCD_USB3 speed, returning the wrong bus_state for HCD_USB31 hosts.

This caused null pointer dereference errors in bus_resume function.

Cc: <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci.h

@@ -1681,7 +1681,7 @@ struct xhci_bus_state {
 
 static inline unsigned int hcd_index(struct usb_hcd *hcd)
 {
-	if (hcd->speed == HCD_USB3)
+	if (hcd->speed >= HCD_USB3)
 		return 0;
 	else
 		return 1;