mlxsw: spectrum_qdisc: Don't use variable array in mlxsw_sp_tclass_congestion_enable

Resolve the sparse warning:
"sparse: Variable length array is used."
Use 2 arrays for 2 PRM register accesses.

Fixes: 96f17e0776c2 ("mlxsw: spectrum: Support RED qdisc offload")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Yuval Mintz <yuvalm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
index c33beac..b5397da 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
@@ -46,7 +46,8 @@
 				  int tclass_num, u32 min, u32 max,
 				  u32 probability, bool is_ecn)
 {
-	char cwtp_cmd[max_t(u8, MLXSW_REG_CWTP_LEN, MLXSW_REG_CWTPM_LEN)];
+	char cwtpm_cmd[MLXSW_REG_CWTPM_LEN];
+	char cwtp_cmd[MLXSW_REG_CWTP_LEN];
 	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
 	int err;
 
@@ -60,10 +61,10 @@
 	if (err)
 		return err;
 
-	mlxsw_reg_cwtpm_pack(cwtp_cmd, mlxsw_sp_port->local_port, tclass_num,
+	mlxsw_reg_cwtpm_pack(cwtpm_cmd, mlxsw_sp_port->local_port, tclass_num,
 			     MLXSW_REG_CWTP_DEFAULT_PROFILE, true, is_ecn);
 
-	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(cwtpm), cwtp_cmd);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(cwtpm), cwtpm_cmd);
 }
 
 static int