nexthop: fix uninitialized variable in nla_put_nh_group_stats()

nexthop: fix uninitialized variable in nla_put_nh_group_stats()

The "*hw_stats_used" value needs to be set on the success paths to prevent
an uninitialized variable bug in the caller, nla_put_nh_group_stats().

Fixes: 5072ae00aea4 ("net: nexthop: Expose nexthop group HW stats to user space")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>