cpufreq: e_powersaver: call CPUFREQ_POSTCHANGE notfier in error cases

In case we have started PRECHANGE notifier and found an error, we
must call POSTCHANGE notifier with freqs.new = freqs.old.

This driver does take care of it, but the POSTCHANGE is called with
freqs.new on errors too, which is incorrect, so fix it.

[rjw: Changelog]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>