- fix OOPS when PST has core_frequency values of zero

FYI: That one have been fixed by Nate Lawson by calling _INI for processors.
I don't know if it is in acpi-ca yet.  Of course, it is still safe
to check if freq is 0.

-- 
Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.