llc2: Remove the station send queue

We only ever put one skb on the send queue, and then immediately
send it.  Remove the queue and call dev_queue_xmit() directly.

This leaves struct llc_station empty, so remove that as well.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>