i2c: mv64xxx: Document the newly introduced allwinner compatible

Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt

@@ -4,7 +4,7 @@
 Required properties :
 
  - reg             : Offset and length of the register set for the device
- - compatible      : Should be "marvell,mv64xxx-i2c"
+ - compatible      : Should be "marvell,mv64xxx-i2c" or "allwinner,sun4i-i2c"
  - interrupts      : The interrupt number
 
 Optional properties :