net: sched: Make FIFO Qdisc offloadable

Invoke ndo_setup_tc() as appropriate to signal init / replacement,
destroying and dumping of pFIFO / bFIFO Qdisc.

A lot of the FIFO logic is used for pFIFO_head_drop as well, but that's a
semantically very different Qdisc that isn't really in the same boat as
pFIFO / bFIFO. Split some of the functions to keep the Qdisc intact.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>