mlxsw: resources: Add Spectrum-2 maximum large key ID resource

Add a resource to make sure we do not exceed the maximum number of
supported large key IDs in a region.

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