Change the uevent notification when the CPU cluster comes back online

Change from KOBJ_POLICY_INIT to KOBJ_ONLINE as ueventd ignores the
POLICY_INIT event. This results in the sysfs permissions for the
CPU frequency and governor not being set correctly and breaks the
PowerHAL power management function.

Change-Id: I3bb8805c48ce3c737a9c9b3c818d4869485dc427