cpufreq: remove race while accessing cur_policy

cpufreq: remove race while accessing cur_policy

While accessing cur_policy during executing events
CPUFREQ_GOV_START, CPUFREQ_GOV_STOP, CPUFREQ_GOV_LIMITS
same mutex lock is not taken, dbs_data->mutex, which leads
to race and data corruption while running continious suspend
resume test.

Bug 1455519

Change-Id: I6b385578c791648681746b749d33f671d00154f3
Signed-off-by: Bibek Basu <bbasu@nvidia.com>
Reviewed-on: http://git-master/r/407589
(cherry picked from commit 893243039ee4785099603dac1f3221311e3c219f)
Reviewed-on: http://git-master/r/409215
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Venkat Moganty <vmoganty@nvidia.com>
Reviewed-by: Puneet Saxena <puneets@nvidia.com>
Reviewed-by: Sai Gurrappadi <sgurrappadi@nvidia.com>