sf: Fix detection of 0.3 hwcomposer

The format was different, so look at the header bits too...

Change-Id: Ibc3d4c9f6bca74d6951041f92e2ecc6189e58c41
sf: Don't do premultiplied alpha blending on the statusbar for hwc <= 0.3

Blending the translucent statusbar with the limited alpha implementation
of older HWC versions is glitch-prone, so don't do that with the compositor
at all

Change-Id: I96b49823b837a5063960d39c0937caea8bb3116a