mlxsw: reg: Add support for tunnel port in SPVID register

Add spvid_tport field which indicates if the port is tunnel port.
When spvid_tport is true, local_port field supposed to be tunnel port
type.

It will be used to configure which Ethertype will be used when VLAN is
pushed at ingress for tunnel port.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>