msm:rq_stats: Add hotplug disable attribute

Register for suspend and resume notifications from kernel. This should
be done as part of core_initcall so as to receive notification as close
as possible to the actual event. Add hotplug_disable attribute to
rq-stats node. Set/clear this attribute based on the suspend/resume events.

CRS-fixed: 452456
Change-Id: I76fee349b57f47df40785e9c2503e2e1cc6e064e
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>
msm:rq_stats: Fix hotplug attribute during the suspend failure

If the system suspend fails, the hotplug_disable attribute remains
set. This prevents any change to core status from mpdecision. Reset
the value of this attribute if the module receives PM_POST_RESTORE
notification.

Change-Id: I22fd639134adbeb8f8f96603e285151480f537ec
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>
msm:rq_stats: Register for Cpufreq policy notification

Currently the load of the system is calculated using the max
frequency that is read during startup(It does not get updated
when the policy changes). As a result, the average load of the
system is incorrectly calculated and the system might not bring
the cpus online to manage the additional load. This
reduces the performance of the system.

To fix this issue, register rq_stats to receive cpufreq policy
notifications. Update the policy's max frequency when a
notification is received and use that value to calculate the load.

Change-Id: Icc78e28c736c170e198f723fd96c13dfb2dafe8a
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>