thermal: cpu_cooling: fix kernel_doc for cpufreq_cooling_device

Simple fixes for making kernel_doc happy about
struct cpufreq_cooling_device. Includes also a minor
spelling fix.

Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
Acked-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>