sched/cpufreq/schedutil: Fix error path mutex unlock

This patch prevents the 'global_tunables_lock' mutex from being
unlocked before being locked.  This mutex is not locked if the
sugov_kthread_create() function fails.

Signed-off-by: Jules Maselbas <jules.maselbas@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Redpath <chris.redpath@arm.com>
Cc: Dietmar Eggermann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Stephen Kyle <stephen.kyle@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: nd@arm.com
Link: http://lkml.kernel.org/r/20180329144301.38419-1-jules.maselbas@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/cpufreq_schedutil.c

@@ -625,10 +625,9 @@ static int sugov_init(struct cpufreq_policy *policy)
 
 stop_kthread:
 	sugov_kthread_stop(sg_policy);
-
-free_sg_policy:
 	mutex_unlock(&global_tunables_lock);
 
+free_sg_policy:
 	sugov_policy_free(sg_policy);
 
 disable_fast_switch: