thermal: cpu_cooling: Name cpufreq cooling devices as cpufreq_cdev

Objects of "struct cpufreq_cooling_device" are named a bit
inconsistently. Lets use cpufreq_cdev everywhere. Also note that the
lists containing such devices is renamed similarly too.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: NLukasz Luba <lukasz.luba@arm.com>
Tested-by: NLukasz Luba <lukasz.luba@arm.com>
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>