cpuidle: teo: Drop utilized from struct teo_cpu

Because the utilized field in struct teo_cpu is only used locally in
teo_select(), replace it with a local variable in that function.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-and-tested-by: Kajetan Puchalski <kajetan.puchalski@arm.com>