ipv4: nexthop: avoid duplicate NHA_HW_STATS_ENABLE on nexthop group dump

ipv4: nexthop: avoid duplicate NHA_HW_STATS_ENABLE on nexthop group dump

Currently NHA_HW_STATS_ENABLE is included twice everytime a dump of
nexthop group is performed with NHA_OP_FLAG_DUMP_STATS. As all the stats
querying were moved to nla_put_nh_group_stats(), leave only that
instance of the attribute querying.

Fixes: 5072ae00aea4 ("net: nexthop: Expose nexthop group HW stats to user space")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260402072613.25262-1-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>