dt-bindings: imx-thermal: Add imx6sll and imx6ul compatible

Currently the dtbs_check for imx6 generates warnings like this:

['fsl,imx6sll-tempmon', 'fsl,imx6sx-tempmon'] is too long

So add them to the devicetree binding.

Signed-off-by: Stefan Wahren <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/thermal/imx-thermal.yaml

···
 
 properties:
   compatible:
-    enum:
-      - fsl,imx6q-tempmon
-      - fsl,imx6sx-tempmon
-      - fsl,imx7d-tempmon
+    oneOf:
+      - enum:
+          - fsl,imx6q-tempmon
+          - fsl,imx6sx-tempmon
+          - fsl,imx7d-tempmon
+      - items:
+          - enum:
+              - fsl,imx6sll-tempmon
+              - fsl,imx6ul-tempmon
+          - const: fsl,imx6sx-tempmon
 
   interrupts:
     description: |