dt-bindings: watchdog: fsl-imx-wdt: add compatible string fsl,ls1021a-wdt

Add compatible string fsl,ls1021a-wdt for ls1021a SoC. fsl,ls1021a-wdt
allow big-endian property.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250522194732.493624-1-Frank.Li@nxp.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Author: nxpfrankli

Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml

@@ -35,6 +35,7 @@ properties:
               - fsl,imx8mp-wdt
               - fsl,imx8mq-wdt
               - fsl,ls1012a-wdt
+              - fsl,ls1021a-wdt
               - fsl,ls1043a-wdt
               - fsl,vf610-wdt
           - const: fsl,imx21-wdt
@@ -102,6 +103,7 @@ allOf:
             contains:
               enum:
                 - fsl,ls1012a-wdt
+                - fsl,ls1021a-wdt
                 - fsl,ls1043a-wdt
     then:
       properties: