mlxsw: spectrum: Move port module mapping before core port init

During port creation, mlxsw_core_port_init() is called with the front
panel port number and the split port sub-number. Currently, this
information is determined by the driver without firmware assistance.

Subsequent patches are going to query this information from firmware,
but this requires the port to be mapped to a module.

Therefore, move port mapping before mlxsw_core_port_init().

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>