net/mlx5: CmdIF, Use async events chain

Remove the explicit call to mlx5_cmd_comp_handler on MLX5_EVENT_TYPE_CMD
and let command interface to register its own handler when its ready.

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

include/linux/mlx5/driver.h

@@ -278,6 +278,8 @@ struct mlx5_cmd_stats {
 };
 
 struct mlx5_cmd {
+	struct mlx5_nb    nb;
+
 	void	       *cmd_alloc_buf;
 	dma_addr_t	alloc_dma;
 	int		alloc_size;