recipes-images: qt5: remove phytec-qt5demo-image.bb
recipes-images: qt5: remove phytec-qt5demo-image.bb

Remove unused, broken and not supported phytec-qt5demo-image. Qt5 will be
integrated in meta-yogurt.

Signed-off-by: Stefan Christ <c04781dbce194802ec6a6311a1200fbcd0141e96@phytec.de>

PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec