util: virhostcpu: factor out frequency parsing

util: virhostcpu: factor out frequency parsing

All different architectures use the same copy-pasted code to parse
processor frequency information from /proc/cpuinfo. Let's extract that
code into a function to avoid repetition.

We now also tolerate if the parsing of /proc/cpuinfo is not successful
and just report a warning instead of bailing out and abandoning the rest
of the CPU information.

Reviewed-by: Marc Hartmayer <mhartmay@linux.vnet.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy@linux.vnet.ibm.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Bjoern Walk <bwalk@linux.vnet.ibm.com>