USB: xhci: Make xhci_handle_event() static.

xhci_handle_event() is now only called from within xhci-ring.c, so make it
static.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index eb4b102..3b962ba 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1964,7 +1964,7 @@
  * This function handles all OS-owned events on the event ring.  It may drop
  * xhci->lock between event processing (e.g. to pass up port status changes).
  */
-void xhci_handle_event(struct xhci_hcd *xhci)
+static void xhci_handle_event(struct xhci_hcd *xhci)
 {
 	union xhci_trb *event;
 	int update_ptrs = 1;