icmp: RCU conversion in icmp_address_reply()

- rcu_read_lock() already held by caller
- use __in_dev_get_rcu() instead of in_dev_get() / in_dev_put()
- remove goto out;

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>