nvme: mark the result argument to nvme_complete_async_event volatile

We'll need that in the PCIe driver soon as we'll read it straight off the
CQ.
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -3344,7 +3344,7 @@ static void nvme_fw_act_work(struct work_struct *work)
 }
 
 void nvme_complete_async_event(struct nvme_ctrl *ctrl, __le16 status,
-		union nvme_result *res)
+		volatile union nvme_result *res)
 {
 	u32 result = le32_to_cpu(res->u32);
 

drivers/nvme/host/nvme.h

@@ -400,7 +400,7 @@ int nvme_sec_submit(void *data, u16 spsp, u8 secp, void *buffer, size_t len,
 		bool send);
 
 void nvme_complete_async_event(struct nvme_ctrl *ctrl, __le16 status,
-		union nvme_result *res);
+		volatile union nvme_result *res);
 
 void nvme_stop_queues(struct nvme_ctrl *ctrl);
 void nvme_start_queues(struct nvme_ctrl *ctrl);