mlxsw: spectrum_qdisc: Drop an always-true condition

The function mlxsw_sp_qdisc_compare() is invoked a couple lines above this
check, which will bounce any requests where this condition does not hold.
Therefore drop it.

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