[CPUFREQ] Quieten the powernow-k7 init printk a little.

[CPUFREQ] Quieten the powernow-k7 init printk a little.
There seem to be quite a few desktop K7 processors which support the
powernow cpuid call, but don't actually offer any powernow scaling.
In which case the driver prints out
"PowerNOW! Technology present. Can scale: nothing" which looks a bit odd,
and just adds to confusion of end-users.
Change things so that we don't print anything at all if we can't do anything.

Also kill some trailing whitespace gremlins that crept in.