Use wakeup reason when FingerPrint sensor wakes up the device

PowerManager can log into BatteryStats the reason for the device being
woken up. This change has the Fingerprint controller report the reason
instead of a default non-descriptive 'wakeUp' reason.

Bug:26209577
Change-Id: I12d80682dad888add139cca586d4b948e9d546e5
(cherry picked from commit 5bcb8bb3)