target/s390x: set has_deprecated_props flag

Now that the deprecated_props is an optional field, the expansion method
must now set the "has_deprecated_props" flag in order for the data to be
output from the response.

Fixes: 448553bb7c (qapi: Make CpuModelExpansionInfo::deprecated-props optional and generic)
Signed-off-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250630024404.940882-1-walling@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

target/s390x/cpu_models_system.c

@@ -252,6 +252,9 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
 
     s390_feat_bitmap_to_ascii(deprecated_feats,
                               &expansion_info->deprecated_props, list_add_feat);
+
+    expansion_info->has_deprecated_props = !!expansion_info->deprecated_props;
+
     return expansion_info;
 }