[BPQ] lockdep: fix false positive

Bpqether is encapsulating AX.25 frames into ethernet frames.  There is a
virtual bpqether device paired with each ethernet devices, so it's normal
to pass through dev_queue_xmit twice for each frame which triggers the
locking detector.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>