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: Viresh Kumar <[email protected]>
Reviewed-by: Lukasz Luba <[email protected]>
Tested-by: Lukasz Luba <[email protected]>
Signed-off-by: Eduardo Valentin <[email protected]>