USB: iowarrior: Push down BKL

I'm pretty sure the mutex is sufficient for all locking but will come
back to that later if the USB folks don't beat me to it. For now get rid
of the old BKL ioctl method and wrap the ioctl handler

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>