soc: qcom: msm_perf: Add timers to exit SINGLE mode

Certain governors may stop sending out notifications once CPUs enter
idle at min frequency.If governor's notifications stop then single mode
will not exit for long time. It can happen only if the exit conditions are
set in such a way that the time taken to exit single mode exceeds the time
for the governor to ramp down, idle out and hence stop sending
notifications leaving the system in single mode indefinitely.

This change adds seperate enter/exit cycle sysfs nodes along with a per
cluster non-deferrable timer for single mode exit. The timer is armed only
when the load starts falling below the exit load threshold and is
cancelled when either the load starts going up or SINGLE mode is exited
due to exceeding exit cycle count. On expiry the timer resets SINGLE mode
and the enter/exit cycle counts.

Change-Id: I02dd3fa8af39ca320e80da6391eb2b1ea635a433
Signed-off-by: Tapas Kumar Kundu <tkundu@codeaurora.org>