nvme-pci: fix sleeping function called from interrupt context

the nvme_handle_cqe() interrupt handler calls nvme_complete_async_event()
but the latter may call nvme_auth_stop() which is a blocking function.
Sleeping functions can't be called in interrupt context

BUG: sleeping function called from invalid context
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/15
Call Trace:
<IRQ>
__cancel_work_timer+0x31e/0x460
? nvme_change_ctrl_state+0xcf/0x3c0 [nvme_core]
? nvme_change_ctrl_state+0xcf/0x3c0 [nvme_core]
nvme_complete_async_event+0x365/0x480 [nvme_core]
nvme_poll_cq+0x262/0xe50 [nvme]

Fix the bug by moving nvme_auth_stop() to fw_act_work
(executed by the nvme_wq workqueue)

Fixes: f50fff73d620 ("nvme: implement In-Band authentication")
Signed-off-by: Maurizio Lombardi <[e-mail]>
Reviewed-by: Jens Axboe <[e-mail]>
Reviewed-by: Sagi Grimberg <[e-mail]>
Signed-off-by: Keith Busch <[e-mail]>

drivers/nvme/host/core.c

···
 				struct nvme_ctrl, fw_act_work);
 	unsigned long fw_act_timeout;
 
+	nvme_auth_stop(ctrl);
+
 	if (ctrl->mtfa)
 		fw_act_timeout = jiffies +
 				msecs_to_jiffies(ctrl->mtfa * 100);
···
 		 * firmware activation.
 		 */
 		if (nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING)) {
-			nvme_auth_stop(ctrl);
 			requeue = false;
 			queue_work(nvme_wq, &ctrl->fw_act_work);
 		}