iio: hid-sensor-attributes: Check sample_frequency/hysteresis write data legitimacy

Neither sample frequency value nor hysteresis value can be set to be a
negative number, check and return "Invalid argument" if they are negative.

If not do this change, sample_frequency will be set into some unknown
value, read hysteresis value after write negative number will return
"Invalid argument".
Signed-off-by: NSong Hongyan <hongyan.song@intel.com>
Acked-by: NSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/common/hid-sensors/hid-sensor-attributes.c

@@ -201,7 +201,7 @@ int hid_sensor_write_samp_freq_value(struct hid_sensor_common *st,
 	int ret;
 
 	if (val1 < 0 || val2 < 0)
-		ret = -EINVAL;
+		return -EINVAL;
 
 	value = val1 * pow_10(6) + val2;
 	if (value) {
@@ -250,6 +250,9 @@ int hid_sensor_write_raw_hyst_value(struct hid_sensor_common *st,
 	s32 value;
 	int ret;
 
+	if (val1 < 0 || val2 < 0)
+		return -EINVAL;
+
 	value = convert_to_vtf_format(st->sensitivity.size,
 				st->sensitivity.unit_expo,
 				val1, val2);