cpufreq: Don't update new_policy on failures

The local variable "new_policy" hasn't been used in the error path of
cpufreq_online() since commit f9f41e3e (cpufreq: Remove policy
create/remove notifiers).  Don't update it in that error path.

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