Revert "thermal: Fix locking in cooling device sysfs update cur_state"

This reverts commit 9c74cd4a.

This is a preparation change for merging android-4.19.21 into
msm-4.19 branch.

Aggregation logic has been added by change
cce57c4487d ("drivers: thermal: Aggregate userspace mitigation request")
for any userspace cooling device request to support multiple governors
to monitor different thermal zones. This locking issue is already taken
care by aggregation logic in cooling device sysfs update cur_state.

Change-Id: Ia868d9e2daf21ef3f9e588e759704e55c40ca24d
Signed-off-by: Ivaylo Georgiev <irgeorgiev@codeaurora.org>