mlxsw: spectrum_router: Replace vPorts with Port-VLAN

We're going to get rid of vPorts completely later in the patchset, but
the router code is self-contained, so it's a good candidate to start the
transition with.

Convert all the functions that expects to operate on a vPort to operate
on a Port-VLAN instead.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>