sched/cpufreq: uclamp: Add clamps for FAIR and RT tasks

Each time a frequency update is required via schedutil, a frequency is
selected to (possibly) satisfy the utilization reported by each
scheduling class. However, when utilization clamping is in use, the
frequency selection should consider userspace utilization clamping
hints.  This will allow, for example, to:

 - boost tasks which are directly affecting the user experience
   by running them at least at a minimum "requested" frequency

 - cap low priority tasks not directly affecting the user experience
   by running them only up to a maximum "allowed" frequency

These constraints are meant to support a per-task based tuning of the
frequency selection thus supporting a fine grained definition of
performance boosting vs energy saving strategies in kernel space.

Add support to clamp the utilization of RUNNABLE FAIR and RT tasks
within the boundaries defined by their aggregated utilization clamp
constraints.

Do that by considering the max(min_util, max_util) to give boosted tasks
the performance they need even when they happen to be co-scheduled with
other capped tasks.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

---
Changes in v7:
 Message-ID: <CAJZ5v0j2NQY_gKJOAy=rP5_1Dk9TODKNhW0vuvsynTN3BUmYaQ@mail.gmail.com>
 - merged FAIR and RT integration patches in this one
 Message-ID: <20190123142455.454u4w253xaxzar3@e110439-lin>
 - dropped clamping for IOWait boost
 Message-ID: <20190122123704.6rb3xemvxbp5yfjq@e110439-lin>
 - fixed go to max for RT tasks on !CONFIG_UCLAMP_TASK