kconfig: qconf: remove unused ConfigList::listView()

I do not know how this function can be useful. In fact, it is unsed.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/qconf.h

@@ -88,10 +88,6 @@ public slots:
 		updateList(NULL);
 		updateAll = false;
 	}
-	ConfigList* listView()
-	{
-		return this;
-	}
 	void addColumn(colIdx idx)
 	{
 		showColumn(idx);