top -M reports 1 CPU 100% busy on idle system

[Johannes Hofmann <johannes.hofmann@xxxxxx>]

After updating a thinkpad X60s to latest head, top -M reports that one
of the CPU's is 100% busy doing interrupts. I doubt that this is true,
as vmstats -i reports a rate of 115 and also the power consumption
seems normal.
However the high load reported on 1 CPU prevents sysutils/estd from
scaling down the CPU frequency.

Cheers,
Johannes