health-check: Fixing cpu efficiency computation

A mistake was done since we only check one core per socket.
So let's compute the ideal performance by multiplying the core
performance by the number of cores.
health-check: Fixing memory consistency report

The report was wrong for the following reason:
- a percentage was shown as a value (in MB/sec)
- a wrong computation were some values were ignored (like 2nd processor
  or 2nd memory result)