PM / devfreq: fix sscanf handling for writable sysfs entries

sscanf returns 0 when an invalid parameter like:
echo -n "a">min_freq
is attempted. Returning back the return result(0) will
cause the command not to return back to command
prompt.

Instead, just return -EINVAL when sscanf does not
return 1.

This is done for min_freq, max_freq and polling_interval

Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/devfreq/devfreq.c

@@ -496,12 +496,11 @@ static ssize_t store_polling_interval(struct device *dev,
 
 	ret = sscanf(buf, "%u", &value);
 	if (ret != 1)
-		goto out;
+		return -EINVAL;
 
 	df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 	ret = count;
 
-out:
 	return ret;
 }
 
@@ -515,7 +514,7 @@ static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr,
 
 	ret = sscanf(buf, "%lu", &value);
 	if (ret != 1)
-		goto out;
+		return -EINVAL;
 
 	mutex_lock(&df->lock);
 	max = df->max_freq;
@@ -529,7 +528,6 @@ static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr,
 	ret = count;
 unlock:
 	mutex_unlock(&df->lock);
-out:
 	return ret;
 }
 
@@ -549,7 +547,7 @@ static ssize_t store_max_freq(struct device *dev, struct device_attribute *attr,
 
 	ret = sscanf(buf, "%lu", &value);
 	if (ret != 1)
-		goto out;
+		return -EINVAL;
 
 	mutex_lock(&df->lock);
 	min = df->min_freq;
@@ -563,7 +561,6 @@ static ssize_t store_max_freq(struct device *dev, struct device_attribute *attr,
 	ret = count;
 unlock:
 	mutex_unlock(&df->lock);
-out:
 	return ret;
 }