photophase: use etc1 compression when available

When avaliable this help to decrease the memory footprint. ETC1 compression
requieres to:
- be supported by opengl
- picture couldn't have an alpha channel
- compression times shouldn't be too higher (< 1000 ms)
- initial pictures doesn't be compressed (to speed up boot)

Change-Id: I87e41db3ca7f2ccb82d4af2763609f11d7e67121
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>