USB: Fix kernel oops with g_ether and Windows

Please find attached patch for
https://bugzilla.kernel.org/show_bug.cgi?id=16023

 problem.


Signed-off-by: Maxim Osipov <maxim.osipov@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>