cpufreq: allow powersave governor as the default without expert mode

The intel_pstate driver only supports the performance and the powersave
governors. With the performance governor ensuring the highest possible
performance settings, userspace tools fail to make any lasting changes.
In order to allow userspace tools to make modifications to the settings,
the powersave governor must be in use. This makes having the powersave
governor as the default convenient for systems where the intel_pstate
driver is being employed. Having to enable expert mode in the kernel
configuration is just a headache for such a trivial task.

This patch applies to all kernel versions 2.6.38 or greater after the
migration from CONFIG_EMBEDDED to CONFIG_EXPERT (6a108a14). Most
importantly, this applies to kernel versions 3.9 or greater when the
intel_pstate driver was introduced.

Signed-off-by: James Geboski <jgeboski@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>