old_cpu_power is wrongly divided by 65535 in ips_monitor()

The variable old_cpu_power is used to save the value of THM_CEC
register. In get_cpu_power(), it will be divided by 65535.

Signed-off-by: minskey guo <chaohong.guo@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>