Staging: iio/accel: Changed data type for val to unsigned long in write_frequency

In lis3102dq_write_frequency() we used a long variable to store the
value parsed from the char* buffer buf, as there only was a
strict_strtol() function to parse values.
Now we have got kstrto* which allows us to convert to the right data
type in most cases.

In this particular function we want to write a frequency value, and it
doesn't make sense to allow negative values here (as Dan Carpenter
pointed out in a previous email).
This means we can now parse the value into an unsigned long and get an
error for invalid (e.g. negative) values.
Signed-off-by: Andreas Ruprecht <rupran@einserver.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/accel/lis3l02dq_core.c

@@ -332,11 +332,11 @@ static ssize_t lis3l02dq_write_frequency(struct device *dev,
 					 size_t len)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
-	long val;
+	unsigned long val;
 	int ret;
 	u8 t;
 
-	ret = strict_strtol(buf, 10, &val);
+	ret = kstrtoul(buf, 10, &val);
 	if (ret)
 		return ret;