Merge branch 'sja1110-dsa-tagging'

Vladimir Oltean says:

====================
DSA tagging driver for NXP SJA1110

This series adds support for tagging data and control packets on the new
NXP SJA1110 switch (supported by the sja1105 driver). Up to this point
it used the sja1105 driver, which allowed it to send data packets, but
not PDUs as those required by STP and PTP.

To accommodate this new tagger which has both a header and a trailer, we
need to refactor the entire DSA tagging scheme, to replace the "overhead"
concept with separate "needed_headroom" and "needed_tailroom" concepts,
so that SJA1110 can declare its need for both.

There is also some consolidation work for the receive path of tag_8021q
and its callers (sja1105 and ocelot-8021q).

Changes in v3:
Rebase in front of the "Port the SJA1105 DSA driver to XPCS" series
which seems to have stalled for now.

Changes in v2:
Export the dsa_8021q_rcv and sja1110_process_meta_tstamp symbols to
avoid build errors as modules.
====================

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