dt-bindings: mmc: renesas,sdhi: Add optional SDnH clock

This only applies to R-Car Gen2 and later generations, so we need to
distinguish.

Signed-off-by: Wolfram Sang <[e-mail]>
Acked-by: Ulf Hansson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Geert Uytterhoeven <[e-mail]>

Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml

···
         - clock-names
         - resets
     else:
-      properties:
-        clocks:
-          minItems: 1
-          maxItems: 2
-        clock-names:
-          minItems: 1
-          items:
-            - const: core
-            - const: cd
+      if:
+        properties:
+          compatible:
+            contains:
+              enum:
+                - renesas,rcar-gen2-sdhi
+                - renesas,rcar-gen3-sdhi
+      then:
+        properties:
+          clocks:
+            minItems: 1
+            maxItems: 3
+          clock-names:
+            minItems: 1
+            uniqueItems: true
+            items:
+              - const: core
+              - enum: [ clkh, cd ]
+              - const: cd
+      else:
+        properties:
+          clocks:
+            minItems: 1
+            maxItems: 2
+          clock-names:
+            minItems: 1
+            items:
+              - const: core
+              - const: cd
 
   - if:
       properties: