mlxsw: cmd: Add QUERY_FW.lag_mode_support

Add QUERY_FW.lag_mode_support, which determines whether
CONFIG_PROFILE.lag_mode is available.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>