thermal/drivers/intel_powerclamp: Constify static thermal_cooling_device_ops

thermal/drivers/intel_powerclamp: Constify static thermal_cooling_device_ops

The only usage of powerclamp_cooling_ops is to pass its address to
thermal_cooling_device_register(), which takes a pointer to const struct
thermal_cooling_device_ops. Make it const to allow the compiler to put
it in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20211128214641.30953-1-rikard.falkeborn@gmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>