[PATCH] USB: drivers/usb/core/: remove unused exports

This patch removes the following unused EXPORT_SYMBOL's:
- hub.c: usb_set_device_state
- usb.c: usb_alloc_dev
- usb.c: usb_disconnect

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>