On EeePC 1015 PED (in Live mode), cpupower.service seemed to start too
early, before /sys/devices/.../scaling_available_governors was there,
and failed as a result. There were no such problems on faster machines,
but still.
Now cpupower.service will start only when 'scaling_available_governors'
file is available. cpupower.path unit handles this. If CPU frequency
scaling is not supported the file will never appear and cpupower.service
will not start at all, which is natural.
Should fix bug #4810.
cpupower will now select the governor automatically during the start of
the service, based on what is available. This can be overridden with
the variables in /etc/sysconfig/cpupower (see the comments there).