mlxsw: spectrum_router: Ignore FIB notification events for non-init namespaces

Since now, the table with same id in multiple netnamespaces were squashed
to a single virtual router. That is not only incorrect, it also causes
error messages when trying to use RALUE register to do double remove
of FIB entries, like this one:

mlxsw_spectrum 0000:03:00.0: EMAD reg access failed (tid=facb831c00007b20,reg_id=8013(ralue),type=write,status=7(bad parameter))

Since we don't allow ports to change namespaces (NETIF_F_NETNS_LOCAL),
and the infrastructure is not yet prepared to handle netnamespaces, just
ignore FIB notification events for non-init namespaces. That is clear to
do since we don't need to offload them.

Fixes: b45f64d1 ("mlxsw: spectrum_router: Use FIB notifications instead of switchdev calls")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>