SystemUI: add missed super window calls

onAttachToWindow() and onDetatchedFromWindow() were added in
d45c6d4f, however they do not call
through to the super PanelView versions of those methods.

Change-Id: I52b4b76835f2704acf08f4134a31ec6e19fd8e31
Signed-off-by: Roman Birg <roman@cyngn.com>