hwmon: (sht21) Update data sheet URLs

The previously used URLs are dead.

Sensirion provides permalinks for their product datasheets at
https://www.sensirion.com/en/about-us/links/.
Signed-off-by: Danilo Bargen <mail@dbrgn.ch>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/sht21

@@ -6,13 +6,13 @@ Supported chips:
     Prefix: 'sht21'
     Addresses scanned: none
     Datasheet: Publicly available at the Sensirion website
-    http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf
+    http://www.sensirion.com/file/datasheet_sht21
 
   * Sensirion SHT25
-    Prefix: 'sht21'
+    Prefix: 'sht25'
     Addresses scanned: none
     Datasheet: Publicly available at the Sensirion website
-    http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf
+    http://www.sensirion.com/file/datasheet_sht25
 
 Author:
   Urs Fleisch <urs.fleisch@sensirion.com>

drivers/hwmon/sht21.c

@@ -16,8 +16,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
  *
- * Data sheet available (5/2010) at
- * http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf
+ * Data sheet available at http://www.sensirion.com/file/datasheet_sht21
  */
 
 #include <linux/module.h>