[CPUFREQ] Change loglevels on powernow-k8 bios error printk's.

If a user has booted with 'quiet', some important messages don't
get displayed which really should. We've seen at least one case
where powernow-k8 stopped working, and the user needed a BIOS update
that they didn't know about.

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