ANDROID: sched/rt: Add schedtune accounting to rt task enqueue/dequeue

rt tasks are currently not eligible for schedtune boosting. Make it so
by adding enqueue/dequeue hooks.

For rt tasks, schedtune only acts as a frequency boosting framework, it
has no impact on placement decisions and the prefer_idle attribute is
not used.

Also prepare schedutil use of boosted util for rt task boosting

With this change, schedtune accounting will include rt class tasks,
however boosting currently only applies to the utilization provided by
fair class tasks. Sum up the tracked CPU utilization applying boost to
the aggregate util instead - this includes RT task util in the boosting
if any tasks are runnable.

Scenario 1, considering one CPU:
1x rt task running, util 250, boost 0
1x cfs task runnable, util 250, boost 50
 previous util=250+(50pct_boosted_250) = 887
 new      util=50_pct_boosted_500      = 762

Scenario 2, considering one CPU:
1x rt task running, util 250, boost 50
1x cfs task runnable, util 250, boost 0
 previous util=250+250                 = 500
 new      util=50_pct_boosted_500      = 762

Scenario 3, considering one CPU:
1x rt task running, util 250, boost 50
1x cfs task runnable, util 250, boost 50
 previous util=250+(50pct_boosted_250) = 887
 new      util=50_pct_boosted_500      = 762

Scenario 4:
1x rt task running, util 250, boost 50
 previous util=250                 = 250
 new      util=50_pct_boosted_250  = 637

Change-Id: Ie287cbd0692468525095b5024db9faac8b2f4878
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
(cherry picked from commit 8e266aebf737262aeca9662254a3e61ccc7f8dec)
[ - Fixed conflicts in sugov related to PELT signals of all classes
  - Fixed conflicts related to boosted_cpu_util being in a different
    location
  - Moved the CFS/RT util aggregation out of schedutil_freq_util to
    ease the integration with SchedTune ]
Signed-off-by: Quentin Perret <quentin.perret@arm.com>