bootanimation: fix usage of LOGW

Change-Id: I1d59df9f44f414d80058a532644cbbb40e22c701
bootanimation: allow using RGB565 instead of ARGB8888

RGB565 uses considerably less memory, and together with texture
cache, it allows us to offer a really smooth bootanimation on
not so powerful devices.

Change-Id: I9da8fd7e6a587b5895519dd0983ec9b8f676771b