ANDROID: sched/fair: schedtune: update before schedutil

When a task is enqueue its boosted value must be accounted on that CPU
to better support the selection of the required frequency.
However, schedutil is (implicitly) updated by update_load_avg() which
always happens before schedtune_{en,de}queue_task(), thus potentially
introducing a latency between boost value updates and frequency
selections.

Let's update schedtune at the beginning of enqueue_task_fair(),
which will ensure that all schedutil updates will see the most
updated boost value for a CPU.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Change-Id: I1038f00600dd43ca38b76b2c5681b4f438ae4036