Merge branch 'mlxsw-Offload-FIFO'

Ido Schimmel says:

====================
mlxsw: Offload FIFO

Petr says:

If an ETS or PRIO band contains an offloaded qdisc, it is possible to
obtain offloaded counters for that band. However, some of the bands will
likely simply contain the default invisible FIFO qdisc, which does not
present the counters.

To remedy this situation, make FIFO offloadable, and offload it by mlxsw
when below PRIO and ETS for the sole purpose of providing counters for the
bands that do not include other qdiscs.

- In patch #1, FIFO is extended to support offloading.
- Patches #2 and #3 restructure bits of mlxsw to facilitate
  the offload logic.
- Patch #4 then implements the offload itself.
- Patch #5 changes the ETS selftest to use the new counters.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>