Remove some Q_WS_MAEMO_6 instances from examples.

Some of this stuff no longer worked (setGraphicsSystem..) and generally speaking
it just doesn't make much sense: widgets on Harmattan were never really a
supported platform.

Change-Id: Ia853c6b3297075f32e51d68a05121f700509632d
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>