ip_local_deliver_finish() already have a rcu_read_lock/unlock, so
the rcu_read_lock/unlock is unnecessary.

See the stack below:
ip_local_deliver_finish
	|
	|
	->icmp_rcv
		|
		|
		->icmp_socket_deliver
Suggested-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDuan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>