IB/mlx5: Declare devx_async_cmd_event_fops static

Avoid that sparse complains about a missing declaration.
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Fixes: 6bf8f22a ("IB/mlx5: Introduce MLX5_IB_OBJECT_DEVX_ASYNC_CMD_FD")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/devx.c

@@ -1704,7 +1704,7 @@ static __poll_t devx_async_cmd_event_poll(struct file *filp,
 	return pollflags;
 }
 
-const struct file_operations devx_async_cmd_event_fops = {
+static const struct file_operations devx_async_cmd_event_fops = {
 	.owner	 = THIS_MODULE,
 	.read	 = devx_async_cmd_event_read,
 	.poll    = devx_async_cmd_event_poll,