mlxsw: spectrum: Introduce port mapping change event processing

Register PMLPE trap and process the port mapping changes delivered
by it by creating related ports. Note that this happens after
provisioning. The INI of the linecard is processed and merged by FW.
PMLPE is generated for each port. Process this mapping change.

Layout of PMLPE is the same as layout of PMLP.

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