cpufreq: mediatek: Fix potential deadlock problem in mtk_cpufreq_set_target

Fix following coccichek error:
./drivers/cpufreq/mediatek-cpufreq.c:199:2-8: preceding lock on line
./drivers/cpufreq/mediatek-cpufreq.c:208:2-8: preceding lock on line

mutex_lock is acquired but not released before return.
Use 'goto out' to help releasing the mutex_lock.

Fixes: c210063b ("cpufreq: mediatek: Add opp notification support")
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/mediatek-cpufreq.c

@@ -196,7 +196,8 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 
 	if (pre_vproc < 0) {
 		dev_err(cpu_dev, "invalid Vproc value: %d\n", pre_vproc);
-		return pre_vproc;
+		ret = pre_vproc;
+		goto out;
 	}
 
 	freq_hz = freq_table[index].frequency * 1000;
@@ -205,7 +206,8 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 	if (IS_ERR(opp)) {
 		dev_err(cpu_dev, "cpu%d: failed to find OPP for %ld\n",
 			policy->cpu, freq_hz);
-		return PTR_ERR(opp);
+		ret = PTR_ERR(opp);
+		goto out;
 	}
 	vproc = dev_pm_opp_get_voltage(opp);
 	dev_pm_opp_put(opp);