Metrics will be published here [1] going forwards, but they have
slightly different scale units. To allow autogenerated metrics to be
added more easily, update the scale units to match.
The more detailed descriptions have also been taken and added to the
common file.
[1]:https://urldefense.com/v3/__https://gitlab.arm.com/telemetry-solution/telemetry-solution/-/tree/main/data/pmu/cpu/__;!!ACWV5N9M2RV99hQ!P1pT5PYzk0os04MQETZD2-22Rp9SCpDzrGV4g-wWDSx0667S3YYkIMArEI9wYBa2SlzR6Jnu2GKRjYJqOHnGrg$
Acked-by: Ian Rogers<irogers@xxxxxxxxxx>
Signed-off-by: James Clark<james.clark@xxxxxxx>