net: Drop hold_rtnl arg from ops_undo_list().

ops_undo_list() first iterates over ops_list for ->pre_exit().

Let's check if any of the ops has ->exit_rtnl() there and drop
the hold_rtnl argument.

Note that nexthop uses ->exit_rtnl() and is built-in, so hold_rtnl
is always true for setup_net() and cleanup_net() for now.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/netdev/20250414170148.21f3523c@kernel.org/


Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250418003259.48017-2-kuniyu@amazon.com


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