qemuMonitorJSONGetStringListProperty: Don't return element count

The only caller doesn't care about the number of elements in the string
list so we don't have to calculate it.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

src/qemu/qemu_monitor_json.c

@@ -6524,7 +6524,7 @@ qemuMonitorJSONGetStringListProperty(qemuMonitor *mon,
     if (!(*strList = virJSONValueObjectGetStringArray(reply, "return")))
         return -1;
 
-    return g_strv_length(*strList);
+    return 0;
 }