dt-bindings: eeprom: at25: Add Anvo ANV32E61W

Document the compatible for ANV32E61W 64kb Serial SPI non-volatile SRAM.
Although it is a SRAM device, it can be accessed through EEPROM
interface. At least until there is no proper SRAM driver support for
it.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/eeprom/at25.txt

@@ -3,6 +3,7 @@ EEPROMs (SPI) compatible with Atmel at25.
 Required properties:
 - compatible : Should be "<vendor>,<type>", and generic value "atmel,at25".
   Example "<vendor>,<type>" values:
+    "anvo,anv32e61w"
     "microchip,25lc040"
     "st,m95m02"
     "st,m95256"