USB: WUSBCORE: fix resource cleanup in error path in __wa_xfer_setup_segs

Use usb_free_urb instead of kfree in error path and point to the correct
URB.  Also remember to clean up the sg list for the URB if it was allocated.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>