mlxsw: spectrum: Update firmware version to xx.2000.2714

The version adds support for 2x50 Gb/s port split option on SN3800
systems.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>