ip-monitor: Include stats events in default and "all" cases

ip-monitor: Include stats events in default and "all" cases

It seems that stats were omitted from `ip monitor` and `ip monitor all`.
Since all other event types are included, include stats as well. Use the
same logic as for nexthops.

Fixes: a05a27c07cbf ("ipmonitor: Add monitoring support for stats events")
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>