power: Avoid reaching req limit of qti perf service.

Without cleaning up the power hint handle,
vendor.qti.hardware.perf@2.0-service is insulted after a while.
ANDR-PERF-MPCTL: Active req limit reached, No optimizations performed
When cleaning up the power hint handle we are able to boost,
as much as we want to do.

Change-Id: I39a69d6b053949578f976fb7ae12f4a9960c50a2
6 files changed