nvme_fc: revise comment on teardown

Per the recommendation by Sagi on:
http://lists.infradead.org/pipermail/linux-nvme/2017-April/009261.html

An extra reference was pointed out.  There's no issue with the
references, but rather a literal interpretation of what the comment
is saying.

Reword the comment to avoid confusion.
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/fc.c

@@ -2532,10 +2532,10 @@ nvme_fc_delete_ctrl_work(struct work_struct *work)
 
 	/*
 	 * tear down the controller
-	 * This will result in the last reference on the nvme ctrl to
-	 * expire, calling the transport nvme_fc_nvme_ctrl_freed() callback.
-	 * From there, the transport will tear down it's logical queues and
-	 * association.
+	 * After the last reference on the nvme ctrl is removed,
+	 * the transport nvme_fc_nvme_ctrl_freed() callback will be
+	 * invoked. From there, the transport will tear down it's
+	 * logical queues and association.
 	 */
 	nvme_uninit_ctrl(&ctrl->ctrl);