intel_mid_thermal: Use struct dev_pm_ops for power management

Make the intel_mid_thermal driver define its PM callbacks through
a struct dev_pm_ops object rather than by using legacy PM hooks
in struct platform_driver.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Durgadoss R <durgadoss.r@intel.com>