mlx5_core: Fix out arg size in access_register command

The output size should be the sum of the core access reg output struct
plus the size of the specific register data provided by the caller.
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/net/ethernet/mellanox/mlx5/core/port.c

@@ -57,7 +57,7 @@ int mlx5_core_access_reg(struct mlx5_core_dev *dev, void *data_in,
 	in->arg = cpu_to_be32(arg);
 	in->register_id = cpu_to_be16(reg_num);
 	err = mlx5_cmd_exec(dev, in, sizeof(*in) + size_in, out,
-			    sizeof(out) + size_out);
+			    sizeof(*out) + size_out);
 	if (err)
 		goto ex2;