dt-bindings: arm: rockchip: Update edgeble-neu6 bindings

Current binding has following compatible combination for SoM, IO board
- NCM6A: edgeble,neural-compute-module-6a,
	 edgeble,neural-compute-module-6a-io
- NCM6B: edgeble,neural-compute-module-6b,
	 edgeble,neural-compute-module-6b-io

This board topology now changes in final revisions, so a common
compatible IO board, NCM6A-IO, is made available for both variants
of SoM: NCM6A and NCM6B, produced by Edgeble AI.

With this change, 6b-io is not as available and 6a; 6b SoM's have the
same compatible IO board as 6a-io. This change is due to the common
optimised design of the IO board made available now in final revisions,
which was not the case in initial revisions.

Update the dt-bindings with this new change.
Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231125142914.57459-1-jagan@edgeble.aiSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -101,16 +101,12 @@ properties:
           - const: edgeble,neural-compute-module-2      # Edgeble Neural Compute Module 2 SoM
           - const: rockchip,rv1126
 
-      - description: Edgeble Neural Compute Module 6(Neu6) Model A SoM based boards
+      - description: Edgeble Neural Compute Module 6(Neu6) SoM based boards
         items:
-          - const: edgeble,neural-compute-module-6a-io  # Edgeble Neural Compute Module 6A IO Board
-          - const: edgeble,neural-compute-module-6a     # Edgeble Neural Compute Module 6A SoM
-          - const: rockchip,rk3588
-
-      - description: Edgeble Neural Compute Module 6(Neu6) Model B SoM based boards
-        items:
-          - const: edgeble,neural-compute-module-6b-io  # Edgeble Neural Compute Module 6B IO Board
-          - const: edgeble,neural-compute-module-6b     # Edgeble Neural Compute Module 6B SoM
+          - const: edgeble,neural-compute-module-6a-io  # Edgeble NCM6A-IO Board
+          - enum:
+              - edgeble,neural-compute-module-6a        # Edgeble Neural Compute Module 6A SoM
+              - edgeble,neural-compute-module-6b        # Edgeble Neural Compute Module 6B SoM
           - const: rockchip,rk3588
 
       - description: Elgin RV1108 R1