Mellanox: Add new mlxsw_spectrum firmware 13.1702.6

This new firmware contains:
    - Support for new types of cables
    - Support for flashing future firmware without reboot
    - Support for Router ARP BC and UC traps
Signed-off-by: Nir Dotan <nird@mellanox.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

WHENCE

@@ -4063,9 +4063,10 @@ 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
+File: mellanox/mlxsw_spectrum-13.1702.6.mfa2
 
 Licence:
- Copyright (c) 2017 Mellanox Technologies, Ltd. All rights reserved.
+ Copyright (c) 2017-2018 Mellanox Technologies, Ltd. All rights reserved.
 
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met: