Framworks: clean up the AOSP tablet icon mess

well.....on grouper the overlay size for the navbar is/was 56dp...so
google added bigger icons then the usual ones into the sw600dp folders.
Well newer tablets have 48dp as default like the phones so the slightly bigger
icons do not fit 100% correct. It is not much but it is noticable.

So all devices have same navbar default height...so all icons should have same size
as well. Just remove the overlay icons so that the system automatically chooses the right
one from the default screen qualifier.

Change-Id: I4e4d87d70996ed1def359149cea829b5794f2448