usb: core: fix below build warning

linux-2.6/drivers/usb/core/hub.c: In function 'usb_disconnect':
linux-2.6/drivers/usb/core/hub.c:2110: warning: 'hub' may be used uninitialized in this function
linux-2.6/drivers/usb/core/hub.c:2111: warning: 'port1' may be used uninitialized in this function

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>