ipv4: adopt dst_dev, skb_dst_dev and skb_dst_dev_net[_rcu]

Use the new helpers as a first step to deal with
potential dst->dev races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250630121934.3399505-8-edumazet@google.com


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