nvme-auth: set explanation code for failure2 msgs

Some error cases were not setting an auth-failure-reason-code-explanation.
This means an AUTH_Failure2 message will be sent with an explanation value
of 0 which is a reserved value.
Signed-off-by: Mark O'Donovan <shiftee@posteo.net>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/auth.c

@@ -838,6 +838,8 @@ static void nvme_queue_auth_work(struct work_struct *work)
 	}
 
 fail2:
+	if (chap->status == 0)
+		chap->status = NVME_AUTH_DHCHAP_FAILURE_FAILED;
 	dev_dbg(ctrl->device, "%s: qid %d send failure2, status %x\n",
 		__func__, chap->qid, chap->status);
 	tl = nvme_auth_set_dhchap_failure2_data(ctrl, chap);