cpupower: rework the "cpupower frequency-info" command

this patch makes two changes to the way that "cpupower
frequancy-info" operates

1. make it so that querying individual values always returns a
   message to the user

currently cpupower frequency info doesn't return anything to the user when
querying an individual value cannot be returned

[root@amd-dinar-09 cpupower]# cpupower -c 4 frequency-info -d
analyzing CPU 4:
[root@amd-dinar-09 cpupower]#

I added messages so that each query prints a message to the terminal

[root@amd-dinar-09 cpupower]# ./cpupower -c 4 frequency-info -d
analyzing CPU 4:
  no or unknown cpufreq driver is active on this CPU
[root@amd-dinar-09 cpupower]#

(this is just one example)

2. change debug_output_one() to use the functions already provided
   by cpufreq-info.c to query individual values of interest.

Signed-off-by: Jacob Tanenbaum <jtanenba@redhat.com>
Signed-off-by: Thomas Renninger <trenn@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>