Remove hardware/qcom/power

 * This is deprecated. It was only used by Nexus devices, and they now
   have the PowerHAL within their individual device repositories.

Change-Id: I39322ff9ce66eeeb84e0893aa320da3eceb03639
Remove QCOM sensors repo

* This is an empty repo on AOSP and not used by any devices.

Change-Id: Ie2355ab94b08390d3bcbefac8c137b3ba545207d
Set up QCOM HAL variants

Change-Id: I1a6897145f34aaed0c03d76f9dea63c8896c76f5