SettingsAccessor: Remove SettingsAccessorPrivate::Settings::isValid

It is unused.

Change-Id: I9cace756479a2af2a1b96a3e4bde790f31b319ae
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/utils/settingsaccessor.cpp

@@ -256,8 +256,6 @@ public:
     class Settings
     {
     public:
-        bool isValid() const;
-
         QVariantMap map;
         FileName path;
     };
@@ -843,13 +841,4 @@ QVariantMap SettingsAccessor::mergeSettings(const QVariantMap &userMap,
     return upgradeSettings(result);
 }
 
-// -------------------------------------------------------------------------
-// SettingsData
-// -------------------------------------------------------------------------
-
-bool SettingsAccessorPrivate::Settings::isValid() const
-{
-    return SettingsAccessor::versionFromMap(map) > -1 && !path.isEmpty();
-}
-
 } // namespace Utils