um: Fix raw interface options

Raw interface initialization needs QDISC_BYPASS. Otherwise
it sees its own packets when transmitting.

Fixes: 49da7e64

 ("High Performance UML Vector Network Driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>