cpufreq: interactive: Replace policy_timer with sched_util hook

Instead of scheduling a timer to run, let's setup an irq_work to
run every time the sched_util hook is called. Due to the way
sched_util works, the hook could be called on any CPU, so we need
to have a hook for each CPU, that funnels down to the right
policy for that CPU. We also need to ignore multiple CPU calls
for the same policy, so keep track of the irq_work that may be in
process and bail out early if one is already running.

Change-Id: I84054afe99edbbc44ac1fdfffaf9d8d4e7d1ab54
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>