Revert "Add support for custom buffer sizes.."

This reverts commit d6eecf50919312c1dd778c5742de72bb98f98f1a.

Conflicts:

	libs/gui/Android.mk
	libs/ui/Android.mk
	libs/ui/GraphicBufferAllocator.cpp

Change-Id: I8a8ef605dffc67a1bf2605c738bb43e801688371