ae-bridge: Change default polygon offset from -0.2 to -1.5.

From forum chat, Paul said :

    (-3.0, -3.0) should work with devices that require the O-2 profile
    (tested just now) and probably with Tegra 2 profile as well, which
    are close. That may be good enough [if we are] targeting mainly
    newer Android devices (most seem to be falling into the O-2 profile
    I've noticed)

    Which reminds me-- at some point we probably should make the O-2
    values (-1.5, -1.5) default when hardware is unknown. Majority of
    older devices were (-.2, -.2) but not sure if that still holds true.