HeadsUp: Only remove heads up if attached to window

Attempting to remove mHeadsUpNoficiationView from the window manager
when it is not currently attached will throw an IllegalArgumentException
so we check if it is attached and if so remove it, otherwise carry on.

As well remove possible left children in statusbarview

Change-Id: Ida916eba496c4183e47288ef24a8a93c46a7eddf
SystemUI: improve one finger notification expansion

Sometimes the quick settings ribbon would eat the initial ACTION_DOWN
setting mInitialTouchY in the expand helper, but we are clearly not in a
notification that we can expand here. So only set the initial y point if
we are inside the notification scrollview.

Change-Id: I877a6d5db4ec02d24f734d3284d554da13608322