Staging: iio/accel: Added a range check for val in store_measurement_mode()

In sca3000_store_measurement_mode() we use val to and it with a mask.
This mask is only two bits long (as we are only interested in the
lowest two bits), so a value bigger than 3 was silently ignored so
far.

Now this function will return -EINVAL, if val is bigger than 3.
Signed-off-by: Andreas Ruprecht <rupran@einserver.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/accel/sca3000_core.c

@@ -389,6 +389,10 @@ sca3000_store_measurement_mode(struct device *dev,
 	ret = kstrtou8(buf, 10, &val);
 	if (ret)
 		goto error_ret;
+	if (val > 3) {
+		ret = -EINVAL;
+		goto error_ret;
+	}
 	ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_MODE, 1);
 	if (ret)
 		goto error_ret;