hikey: powerHAL: Update PowerHAL for top-app category and other tweaks

The initial EAS hikey powerhal was added before N was released, which
introduced the top-app category. So refactor the code to use top-app.

This also tweaks the build so that the module can be more easily
reused on other hardware.

Change-Id: I2847cbf62ea45b15fa2b8d3ee249c153cea351b0
Signed-off-by: John Stultz <john.stultz@linaro.org>
3 files changed