drivers: lpm-levels: use correct CPUHP notifications for QoS

Adding and removing dev PM QoS notifications uses mutex lock and
therefore cannot be called from CPU starting notifications. Update QoS
notifier in a stage when interrupts are allowed.

Change-Id: I21ce6a23d51e97d9f05e96a1772c028c4760ec7d
Signed-off-by: Lina Iyer <ilina@codeaurora.org>