rtc: pcf2127: Fix the datasheet URL

The current datasheet URL is no longer valid.

Replace with a valid one.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210603143447.2223353-1-festevam@gmail.com

drivers/rtc/rtc-pcf2127.c

@@ -10,7 +10,7 @@
  *
  * based on the other drivers in this same directory.
  *
- * Datasheet: http://cache.nxp.com/documents/data_sheet/PCF2127.pdf
+ * Datasheet: https://www.nxp.com/docs/en/data-sheet/PCF2127.pdf
  */
 
 #include <linux/i2c.h>