wusb: make ep0_reinit available for modules

We need to be able to call ep0_reinit() [renamed to usb_ep0_reinit()]
from the WUSB security code. The reason is that when we authenticate
the device, it's address changes (from having bit 7 set to having it
cleared). Thus, we need to signal the USB stack to reinitialize EP0,
so the status with the previous address kept at the HCD layer is
cleared and properly reinitialized.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>