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: NMarc Hartmayer <mhartmay@linux.vnet.ibm.com>
Reviewed-by: NBoris Fiuczynski <fiuczy@linux.vnet.ibm.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>
Signed-off-by: NBjoern Walk <bwalk@linux.vnet.ibm.com>