sgw: multi-sgw mode is only supported on IPv4
sgw: multi-sgw mode is only supported on IPv4

Signed-off-by: Ferry Huberts <66e11f9f5d965b69497c7e73d5e808f8b13c1218@pelagic.nl>

cholin/olsrd,cholin/olsrd,diogomg/olsrd,sebkur/olsrd,diogomg/olsrd-binary-heap,diogomg/olsrd-binary-heap,diogomg/olsrd,sebkur/olsrd,diogomg/olsrd-binary-heap,diogomg/olsrd,sebkur/olsrd,sebkur/olsrd,diogomg/olsrd,cholin/olsrd,diogomg/olsrd,diogomg/olsrd-binary-heap,diogomg/olsrd,cholin/olsrd,diogomg/olsrd-binary-heap,sebkur/olsrd,diogomg/olsrd-binary-heap,diogomg/olsrd-binary-heap,diogomg/olsrd,sebkur/olsrd,cholin/olsrd