mlxsw: spectrum: Unsplit the vFID range

Previous commit deprecated the vFIDs used to get traffic to the CPU
('port_vfids'). Thus, we now use the vFIDs as god intended and the
artificial split is no longer needed.

Rename functions and variables to reflect that.

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>