net: dsa: mv88e6xxx: replace VTU violation prints with trace points

It is possible to trigger these VTU violation messages very easily,
it's only necessary to send packets with an unknown VLAN ID to a port
that belongs to a VLAN-aware bridge.

Do a similar thing as for ATU violation messages, and hide them in the
kernel's trace buffer.

New usage model:

$ trace-cmd list | grep mv88e6xxx
mv88e6xxx
mv88e6xxx:mv88e6xxx_vtu_miss_violation
mv88e6xxx:mv88e6xxx_vtu_member_violation
$ trace-cmd report

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Saeed Mahameed <saeed@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>