[CPUFREQ] Remove unneeded errata workaround from p4-clockmod.

This workaround unnecessarily cripples functionality to work
around an errata that doesn't seem possible to hit due to
us using the automatic clock throttling in the p4 mcheck code.

See http://lkml.org/lkml/2006/10/28/148

 for complete reasoning
and lack of disconsent.

Signed-off-by: Dave Jones <davej@redhat.com>