pico: Disable Atlas service
Disable Atlas service to avoid memory overhaed caused by it.

Drawbacks in Atlas service:
- Fixed size of canvas: whether the drawebles are in use or not always
                        resides in memory.
- Choosing drawables: It chooses the drawables to pre-load based on
                        dimensions, rather than number of requested apps.

Change-Id: I0c46ebe3946f1a3b0cd8c436f97e090f4da2c552