cpufrequtils: Remove proc compile option and interfaces

proc cpufreq kernel support is deprecated since the beginning of 2.6?)
If someone still likes to have support for the 2.4 cpufreq proc
interface one has to pick out an old cpufrequtils version
from now on...

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>