We have a function to calculate this, so update the code to use the function.

Change-ID: Ia345b6fe6ec7f0b2dcf1199471b0d0f959ad3908
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: NKavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>