thermal: devfreq_cooling: Appease the kernel-doc deity

Fix up the following warnings with make W=1:

linux.git/drivers/thermal/devfreq_cooling.c:68: warning: Function
parameter or member 'capped_state' not described in
'devfreq_cooling_device'
linux.git/drivers/thermal/devfreq_cooling.c:593: warning: Function
parameter or member 'cdev' not described in 'devfreq_cooling_unregister'
linux.git/drivers/thermal/devfreq_cooling.c:593: warning: Excess
function parameter 'dfc' description in 'devfreq_cooling_unregister'

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/7059d82472fe12139fc7a3379c5b9716a23cce5c.1574242756.git.amit.kucheria@linaro.org