net: sparx5: replace SPX5_PORTS with n_ports

The Sparx5 VCAP implementation uses the SPX5_PORTS symbol to iterate over
the 65 front ports of Sparx5. Replace the use with the n_ports constant
from the match data, which translates to 65 of Sparx5 and 30 on lan969x.

Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Reviewed-by: Jens Emil Schulz Østergaard <jensemil.schulzostergaard@microchip.com>
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>