net: dsa: mediatek: add VLAN support for MT7530

MT7530 can treat each port as either VLAN-unaware port or VLAN-aware port
through the implementation of port matrix mode or port security mode on
the ingress port, respectively. On one hand, Each port has been acting as
the VLAN-unaware one whenever the device is created in the initial or
certain port joins or leaves into/from the bridge at the runtime. On the
other hand, the patch just filling the required callbacks for VLAN
operations is achieved via extending the port to be into port security
mode when the port is configured as VLAN-aware port. Which mode can make
the port be able to recognize VID from incoming packets and look up VLAN
table to validate and judge which port it should be going to. And the
range for VID from 1 to 4094 is valid for the hardware.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>