net: sparx5: expose some sparx5 VCAP symbols

In preparation for lan969x VCAP support, expose the following symbols for
use by the lan969x VCAP implementation:

- The symbols SPARX5_*_LOOKUPS defines the number of lookups in each
  VCAP instance.  These are the same for lan969x. Move them to the
  header file.

- The struct sparx5_vcap_inst encapsulates information about a single
  VCAP instance. Move this struct to the header file and declare the
  sparx5_vcap_inst_cfg as extern.

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>