Fix ksysguard acpi cooling devices

Summary: The cooling devices state never changed from zero. It was wrongly calculated as a	fraction from 0 to 1, instead of a percentage.

Reviewers: davidedmundson

Reviewed By: davidedmundson

Subscribers: ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D24998