dt-bindings: mfd: Add link to ROHM BD71847 Datasheet

ROHM BD71847 PMIC datasheet was published.
Add datasheet link for BD71847 as well.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt

@@ -8,6 +8,8 @@ and 6 LDOs.
 
 Datasheet for BD71837 is available at:
 https://www.rohm.com/datasheet/BD71837MWV/bd71837mwv-e
+Datasheet for BD71847 is available at:
+https://www.rohm.com/datasheet/BD71847AMWV/bd71847amwv-e
 
 Required properties:
  - compatible		: Should be "rohm,bd71837" for bd71837