The frequencies are in MHz (i.e. a value of 1000 represents 1GHz). The
frequencies are rounded to the nearest whole MHz.
While here, rename and re-type bus_frequency, processor_frequency and
itc_frequency to bus_freq, cpu_freq and itc_freq and make them static.
As unsigned integers, the hw.freq.cpu sysctl can more easily be made
generic (across all architectures) making porting easier.
MFC after: 3 days
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