PM: docs: intel_pstate: fix Active Mode w/o HWP paragraph

P-state selection algorithm (powersave or performance) is selected by
echoing the desired choice to scaling_governor sysfs attribute and not
to scaling_cur_freq (as currently stated).

Fix it.

Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>