drivers: cpu_cooling: Remove cooling list lock during post suspend handling

There is a possible deadlock scenario in cpu cooling device when
thermal core isolation condition, core hotplug and resume contexts
are running concurrently. Core hotplug context takes hotplug framework
lock and waiting for cpu cooling list lock and the same time the post
suspend context is holding cpu cooling list lock and waiting for
hotplug framework lock to isolate core due to thermal condition.

Since cpu cooling device list addition and deletion are not a frequent
call and addition is done once during boot. So it is not expected to
mutate cpu cooling device list on post boot. Remove cooling list lock
safely from post suspend path to avoid this dead lock scenario.

Change-Id: Iec02a3050082ad28826989062e9f3717d50cd3fd
Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@codeaurora.org>