dt-bindings: power: apple,pmgr-pwrstate: Add t6020 compatible

After discussion with the devicetree maintainers we agreed to not extend
lists with the generic compatible "apple,pmgr-pwrstate" anymore [1]. Use
"apple,t8103-pmgr-pwrstate" as base compatible as it is the SoC the
driver and bindings were written for.

The implementation on Apple M2 Pro/Max/Ultra SoCs is compatible so add
its per-SoC compatible with the new base.

[1]: https://lore.kernel.org/asahi/12ab93b7-1fc2-4ce0-926e-c8141cfe81bf@kernel.org/

Reviewed-by: Neal Gompa <neal@gompa.dev>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Janne Grunau <j@jannau.net>

Documentation/devicetree/bindings/power/apple,pmgr-pwrstate.yaml

@@ -29,17 +29,22 @@ description: |
 
 properties:
   compatible:
-    items:
-      - enum:
-          - apple,s5l8960x-pmgr-pwrstate
-          - apple,t7000-pmgr-pwrstate
-          - apple,s8000-pmgr-pwrstate
-          - apple,t8010-pmgr-pwrstate
-          - apple,t8015-pmgr-pwrstate
-          - apple,t8103-pmgr-pwrstate
-          - apple,t8112-pmgr-pwrstate
-          - apple,t6000-pmgr-pwrstate
-      - const: apple,pmgr-pwrstate
+    oneOf:
+      - items:
+          - enum:
+              # Do not add additional SoC to this list.
+              - apple,s5l8960x-pmgr-pwrstate
+              - apple,t7000-pmgr-pwrstate
+              - apple,s8000-pmgr-pwrstate
+              - apple,t8010-pmgr-pwrstate
+              - apple,t8015-pmgr-pwrstate
+              - apple,t8103-pmgr-pwrstate
+              - apple,t8112-pmgr-pwrstate
+              - apple,t6000-pmgr-pwrstate
+          - const: apple,pmgr-pwrstate
+      - items:
+          - const: apple,t6020-pmgr-pwrstate
+          - const: apple,t8103-pmgr-pwrstate
 
   reg:
     maxItems: 1