- Mechanically convert to if_inc_counter() the rest of counters.
- Do not set if_collisions on interrupt, read them in ti_get_counter().
- Add missing bus_dmamap_sync(BUS_DMASYNC_PREREAD) in ti_ioctl2(). [1]

Submitted by:	mav [1]
- Provide lagg_proto_attach(), lagg_proto_detach().
- Make detach a protocol method in lagg_protos.
- Simplify code to lookup protocols.

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