cpufreq: intel_pstate: Skip unnecessary PID resets on init

PID controller parameters only need to be initialized if the
get_target_pstate_use_performance() P-state selection routine
is going to be used.  It is not necessary to initialize them
otherwise, so don't do that.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>