provide overrides for hwui memory limits for xxhdpi phones

Change-Id: I8b369619cd07530d0468a5449da30f338c13c7d2
Add heap configuration for 1080p phones with 2048m

 * Increase heap start size to 16m to minimize GC with larger bitmaps

Change-Id: I8fbba2e5a2a2cf2d7a6898ca6bae8639d6cf5a19