QmlProfiler: Clean up MemoryUsageModel

Don't reimplement locationFromTypeId, make methods public when they are
public in the base class, remove redundant QVariant ctors, inline
memoryTypeName() into the only place where it's used.

Change-Id: I5d780cf27c90a277c13b117c25c80ccce5a4182b
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>

src/plugins/qmlprofiler/memoryusagemodel.h

@@ -67,7 +67,6 @@ public:
     QVariantList labels() const override;
     QVariantMap details(int index) const override;
 
-protected:
     bool accepted(const QmlEventType &type) const override;
     void loadEvent(const QmlEvent &event, const QmlEventType &type) override;
     void finalize() override;
@@ -82,8 +81,6 @@ private:
         qint64 startTime;
     };
 
-    static QString memoryTypeName(int type);
-
     QVector<MemoryAllocationItem> m_data;
     QStack<RangeStackFrame> m_rangeStack;
     qint64 m_maxSize = 1;