net/mlx5: E-Switch, Check group pointer before reading bw_share value

If log_esw_max_sched_depth is not supported group pointer of the vport
is NULL. Hence, check the pointer before reading bw_share value.

Fixes: 0fe132ea ("net/mlx5: E-switch, Allow to add vports to rate groups")
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c

@@ -130,7 +130,7 @@ static u32 esw_qos_calculate_min_rate_divider(struct mlx5_eswitch *esw,
 	/* If vports min rate divider is 0 but their group has bw_share configured, then
 	 * need to set bw_share for vports to minimal value.
 	 */
-	if (!group_level && !max_guarantee && group->bw_share)
+	if (!group_level && !max_guarantee && group && group->bw_share)
 		return 1;
 	return 0;
 }