msm: cpufreq: fix a race between hotplug and cpufreq

When msm_cpufreq_target() is called without holding the policy
semaphore, there is a rare chance that the cpu gets hotplugged in
the acpuclk_set_rate. The probability of this issue increases
when cross-calling is used or using interactive governor which
tries to set all cpu frequencies from a single thread.

Add a hotplug notifier and set the device_suspended flag holding
the suspend mutex, when cpu is going down. This mutex is always
held when frequency changes are done.

Change-Id: Ide3aa6927ad60d2512d63761c51bb15117461250
Signed-off-by: Narayanan Gopalakrishnan <nargop@codeaurora.org>
(cherry picked from commit 56f5a6de7f2ab48ed0538da727ad52673fb801a2)

Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
msm: cpufreq: Implement suspend/resume for cpufreq driver

Cpufreq suspend variable get's updated in kernel pm notifier
callback which gets called in process context. This will create
window where cpufreq governor may try to change the frequency
before suspend variable is updated while resume.

Define suspend/resume for cpufreq driver to update suspend variable
in atomic context.

Don't update the policy->cur upon cpufreq driver failure.

CRs-fixed: 423791
Change-Id: Id78705f5c3b8bf801c6253e9362299280903769f
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>

Conflicts:
	arch/arm/mach-msm/cpufreq.c