nvmet-fc: add a missing __rcu annotation to nvmet_fc_tgt_assoc.queues

Make sparse happy after the recent conversion to RCU lookups.

Fixes: 4e2f02bf ("nvmet-fc: use RCU proctection for assoc_list")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: James Smart <james.smart@broadcom.com>

drivers/nvme/target/fc.c

@@ -165,7 +165,7 @@ struct nvmet_fc_tgt_assoc {
 	struct nvmet_fc_hostport	*hostport;
 	struct nvmet_fc_ls_iod		*rcv_disconn;
 	struct list_head		a_list;
-	struct nvmet_fc_tgt_queue	*queues[NVMET_NR_QUEUES + 1];
+	struct nvmet_fc_tgt_queue __rcu	*queues[NVMET_NR_QUEUES + 1];
 	struct kref			ref;
 	struct work_struct		del_work;
 	struct rcu_head			rcu;