Revert "overall_stats: forward port to kernel 3.4+"

This reverts commit faf6ab59f687dd7d8c649f1b8aa8aa61c4be83dc.
Revert "overall_stats: make dual/quad core stats configurable via meunconfig"

This reverts commit 2f65841356b53743bd265c4bd0a1e4d4d531ed5e.
Revert "overall_stats: add overall stats for all available cores"

This reverts commit c4d34f93c5435afc8d2fcaa6651317b07902f0b9.