thermal: tegra: soctherm: add const to struct thermal_cooling_device_ops

Correct the typecast with const to struct thermal_cooling_device_ops.
It is the last argument to the function thermal_of_cooling_device_register
and this argument is of type const. So, declare this structure
thermal_cooling_device_ops as constant.

Signed-off-by: sumeet p <srplinux2008@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>