rtnetlink: fix netns leak with rtnl_setlink()

A call to rtnl_nets_destroy() is needed to release references taken on
netns put in rtnl_nets.

CC: stable@vger.kernel.org
Fixes: 636af13f ("rtnetlink: Register rtnl_dellink() and rtnl_setlink() with RTNL_FLAG_DOIT_PERNET_WIP.")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250205221037.2474426-1-nicolas.dichtel@6wind.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>