dt-bindings: hwmon: (pmbus/isl68137) Add RAA229621 support

Add device type support for raa229621

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Chiang Brian <chiang.brian@inventec.com>
Link: https://lore.kernel.org/r/20250605040134.4012199-2-chiang.brian@inventec.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: BrianChiang0425

Documentation/devicetree/bindings/hwmon/pmbus/isil,isl68137.yaml

@@ -56,6 +56,7 @@ properties:
       - renesas,raa228228
       - renesas,raa229001
       - renesas,raa229004
+      - renesas,raa229621
 
   reg:
     maxItems: 1