net: dsa: point out the tail taggers

The Marvell 88E6060 uses tag_trailer.c and the KSZ8795, KSZ9477 and
KSZ9893 switches also use tail tags.

Tell that to the DSA core, since this makes a difference for the flow
dissector. Most switches break the parsing of frame headers, but these
ones don't, so no flow dissector adjustment needs to be done for them.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>