cpufrequtils: Don't preserve host user permissions

The makefile installs the generated libcpufreq with 'cp -fpR'
preserving the user and group of the builder on the host system yielding
errors like this:

  WARNING: log_check: warning: group pulse does not exist - using root

Really, this library should be installed with root user and group
ownership so override the meaning of 'CP' to simply 'cp'.

Signed-off-by: Ash Charles <ashcharles@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>