dt-bindings: hwmon: Document ibm,cffps2 compatible string

Document the compatible string for version 2 of the IBM CFFPS PSU.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/1567192263-15065-2-git-send-email-eajames@linux.ibm.comReviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/ibm,cffps1.txt

-Device-tree bindings for IBM Common Form Factor Power Supply Version 1
-----------------------------------------------------------------------
+Device-tree bindings for IBM Common Form Factor Power Supply Versions 1 and 2
+-----------------------------------------------------------------------------
 
 Required properties:
- - compatible = "ibm,cffps1";
+ - compatible				: Must be one of the following:
+						"ibm,cffps1"
+						"ibm,cffps2"
  - reg = < I2C bus address >;		: Address of the power supply on the
 					  I2C bus.