mfd: dt bindings: add BD71847 device-tree binding documentation

Add ROHM BD71847 Power Management IC MFD binding information to
device-tree binding documents.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

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

-* ROHM BD71837 Power Management Integrated Circuit bindings
+* ROHM BD71837 and BD71847 Power Management Integrated Circuit bindings
 
-BD71837MWV is a programmable Power Management IC for powering single-core,
-dual-core, and quad-core SoCs such as NXP-i.MX 8M. It is optimized for
-low BOM cost and compact solution footprint. It integrates 8 Buck
-egulators and 7 LDOs to provide all the power rails required by the SoC and
-the commonly used peripherals.
+BD71837MWV and BD71847MWV are programmable Power Management ICs for powering
+single-core, dual-core, and quad-core SoCs such as NXP-i.MX 8M. They are
+optimized for low BOM cost and compact solution footprint. BD71837MWV
+integrates 8 Buck regulators and 7 LDOs. BD71847MWV contains 6 Buck regulators
+and 6 LDOs.
 
-Datasheet for PMIC is available at:
+Datasheet for BD71837 is available at:
 https://www.rohm.com/datasheet/BD71837MWV/bd71837mwv-e
 
 Required properties:
- - compatible		: Should be "rohm,bd71837".
+ - compatible		: Should be "rohm,bd71837" for bd71837
+				    "rohm,bd71847" for bd71847.
  - reg			: I2C slave address.
  - interrupt-parent	: Phandle to the parent interrupt controller.
  - interrupts		: The interrupt line the device is connected to.