dt-bindings: watchdog: fsl-imx7ulp-wdt: Add i.MX94 support

Add compatible string "fsl,imx94-wdt" for the i.MX94 chip, which is
backward compatible with i.MX93. Set it to fall back to "fsl,imx93-wdt".

Signed-off-by: Frank Li <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

Documentation/devicetree/bindings/watchdog/fsl-imx7ulp-wdt.yaml

···
           - const: fsl,imx8ulp-wdt
           - const: fsl,imx7ulp-wdt
       - const: fsl,imx93-wdt
+      - items:
+          - enum:
+              - fsl,imx94-wdt
+          - const: fsl,imx93-wdt
 
   reg:
     maxItems: 1