dt-bindings: memory: add DDR4 channel compatible

Add in the memory channel binding the DDR4 compatible to support DDR4
memory channel.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Clément Le Goffic <legoffic.clement@gmail.com>
Link: https://patch.msgid.link/20251118-b4-ddr-bindings-v9-4-a033ac5144da@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

Documentation/devicetree/bindings/memory-controllers/ddr/jedec,sdram-channel.yaml

@@ -19,6 +19,7 @@ maintainers:
 properties:
   compatible:
     enum:
+      - jedec,ddr4-channel
       - jedec,lpddr2-channel
       - jedec,lpddr3-channel
       - jedec,lpddr4-channel
@@ -61,6 +62,15 @@ patternProperties:
       - reg
 
 allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: jedec,ddr4-channel
+    then:
+      patternProperties:
+        "^rank@[0-9]+$":
+          $ref: /schemas/memory-controllers/ddr/jedec,ddr4.yaml#
   - if:
       properties:
         compatible: