selftests: mlxsw: qos_lib: Drop __mlnx_qos

Now that the two users of this helper have been converted to iproute2 dcb,
it is not necessary anymore. Drop it.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/mlxsw/qos_lib.sh

@@ -82,17 +82,3 @@ bail_on_lldpad()
 		fi
 	fi
 }
-
-__mlnx_qos()
-{
-	local err
-
-	mlnx_qos "$@" 2>/dev/null
-	err=$?
-
-	if ((err)); then
-		echo "Error ($err) in mlnx_qos $@" >/dev/stderr
-	fi
-
-	return $err
-}