staging: iio: tsl2583: fix format string warnings

Fixed the following warnings (reported by cppcheck):
[drivers/staging/iio/light/tsl2583.c:695]: (warning) %d in format string (no. 1)
requires 'int' but the argument type is 'unsigned int'.
[drivers/staging/iio/light/tsl2583.c:695]: (warning) %d in format string (no. 2)
requires 'int' but the argument type is 'unsigned int'.
[drivers/staging/iio/light/tsl2583.c:695]: (warning) %d in format string (no. 3)
requires 'int' but the argument type is 'unsigned int'.
Signed-off-by: Asaf Vertz <asaf.vertz@tandemg.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/light/tsl2583.c

@@ -692,7 +692,7 @@ static ssize_t taos_luxtable_show(struct device *dev,
 	int offset = 0;
 
 	for (i = 0; i < ARRAY_SIZE(taos_device_lux); i++) {
-		offset += sprintf(buf + offset, "%d,%d,%d,",
+		offset += sprintf(buf + offset, "%u,%u,%u,",
 				  taos_device_lux[i].ratio,
 				  taos_device_lux[i].ch0,
 				  taos_device_lux[i].ch1);