native: add flag to disable legacy sensors fusion

Causes problems on all p31xx devices.
http://pastebin.com/PabjFVWP

Change-Id: Iac9a913e0984d7e9e419772215d3fb3d1a0cb5e8
Merge branch 'cm-10.1' of https://github.com/CyanogenMod/android_frameworks_native into optima