UPSTREAM: cpufreq: schedutil: enable fast switch earlier

The fast_switch_enabled flag will be used by both sugov_policy_alloc()
and sugov_policy_free() with a later patch.

Prepare for that by moving the calls to enable and disable it to the
beginning of sugov_init() and end of sugov_exit().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 4a71ce4348bb61740d411822357061f8bf870f4c)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Change-Id: Ia174f423ca02d59360657ac2e77a5098ce5cf99c