android: ion: do not defer free for carveout heap

android: ion: do not defer free for carveout heap

Carved out heaps allocate buffers from a memory pool of with a limited
size. If it frees buffers in deferred manner, the heap may not be
available in a rare condition by unexpected external fragmentations.
Let's think about the following scenario in a 10MB carveout pool:
  1. allocated 4MB @ +0MB
  2. allocated 2MB @ +4MB
  3. freed 1 but defferred
  4. freed 2 but defferred
  5. allocated 3MB @ +6MB
  6. returned buffer 1 and 2 to the heap.
  7. allocated 4MB @ +0MB
  8. allocation of 3MB failed due to the fragmentation.

Any defferred behavior to the very limited resources is harmful.

Change-Id: I0a64fdec56f0ec1992c20f8ccd50d5c7fbfa8d40
Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>