Mellanox: Add new mlxsw_spectrum firmware 13.1620.192

This new firmware contains:
	- Support for auto-neg disable mode
Signed-off-by: Tal Bar <talb@mellanox.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

WHENCE

@@ -3898,6 +3898,7 @@ Driver: mlxsw_spectrum - Mellanox Spectrum switch
 
 File: mellanox/mlxsw_spectrum-13.1420.122.mfa2
 File: mellanox/mlxsw_spectrum-13.1530.152.mfa2
+File: mellanox/mlxsw_spectrum-13.1620.192.mfa2
 
 Licence:
  Copyright (c) 2017 Mellanox Technologies, Ltd. All rights reserved.