dt-bindings: display: rockchip: analogix-dp: Fix hclk as third clock for RK3588

RK3588 eDP controller requires HCLK_VO1 to access the VO1 GRF
registers and enable the video datapath.

Previously, the clock was enabled implicitly via the 'rockchip,vo-grf'
phandle reference, which allowed the eDP to work without explicitly
managing the hclk_vo1 clock. However, this is not safe or explicit.

To make the clock dependency explicit, enforce per-SoC clock-names
requirements:
 - RK3288: 2 clocks (dp, pclk)
 - RK3399: 3 clocks (dp, pclk, grf)
 - RK3588: 3 clocks (dp, pclk, hclk)

Do not reuse the 'grf' clock name for RK3588 because it represents
a different clock with distinct control logic:
- The 'grf' clock is only for GRF register access and is toggled
  dynamically during register access.
- The 'hclk' clock controls both GRF access and video datapath
  gating, and must remain enabled during probe.

Fixes: f855146263 ("dt-bindings: display: rockchip: analogix-dp: Add support for RK3588")
Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patch.msgid.link/20260601065100.1103873-2-damon.ding@rock-chips.com

Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml

@@ -26,7 +26,9 @@ properties:
     items:
       - const: dp
       - const: pclk
-      - const: grf
+      - enum:
+          - grf
+          - hclk
 
   power-domains:
     maxItems: 1
@@ -60,6 +62,35 @@ required:
 allOf:
   - $ref: /schemas/display/bridge/analogix,dp.yaml#
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - rockchip,rk3288-dp
+    then:
+      properties:
+        clocks:
+          maxItems: 2
+        clock-names:
+          maxItems: 2
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - rockchip,rk3399-edp
+    then:
+      properties:
+        clocks:
+          minItems: 3
+        clock-names:
+          items:
+            - const: dp
+            - const: pclk
+            - const: grf
+
   - if:
       properties:
         compatible:
@@ -68,6 +99,13 @@ allOf:
               - rockchip,rk3588-edp
     then:
       properties:
+        clocks:
+          minItems: 3
+        clock-names:
+          items:
+            - const: dp
+            - const: pclk
+            - const: hclk
         resets:
           minItems: 2
         reset-names: