nvme: fc: provide a descriptive error

Provide a descriptive error in case an lport to rport association
isn't found when creating the FC-NVME controller.

Currently it's very hard to debug the reason for a failed connect
attempt without a look at the source.
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NJames Smart  <james.smart@broadcom.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>

drivers/nvme/host/fc.c

@@ -3284,6 +3284,8 @@ nvme_fc_create_ctrl(struct device *dev, struct nvmf_ctrl_options *opts)
 	}
 	spin_unlock_irqrestore(&nvme_fc_lock, flags);
 
+	pr_warn("%s: %s - %s combination not found\n",
+		__func__, opts->traddr, opts->host_traddr);
 	return ERR_PTR(-ENOENT);
 }