dt-bindings: PCI: mediatek-gen3: add support for mt7986

Add compatible string and clock-definition for mt7986. It needs 4 clocks
for PCIe, define them in binding.

Link: https://lore.kernel.org/r/20221127114142.156573-5-linux@fw-web.de
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Jianjun Wang <jianjun.wang@mediatek.com>

Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml

@@ -48,6 +48,7 @@ properties:
     oneOf:
       - items:
           - enum:
+              - mediatek,mt7986-pcie
               - mediatek,mt8188-pcie
               - mediatek,mt8195-pcie
           - const: mediatek,mt8192-pcie
@@ -84,9 +85,11 @@ properties:
       enum: [ phy, mac ]
 
   clocks:
+    minItems: 4
     maxItems: 6
 
   clock-names:
+    minItems: 4
     maxItems: 6
 
   assigned-clocks:
@@ -169,6 +172,20 @@ allOf:
             - const: tl_32k
             - const: peri_26m
             - const: peri_mem
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - mediatek,mt7986-pcie
+    then:
+      properties:
+        clock-names:
+          items:
+            - const: pl_250m
+            - const: tl_26m
+            - const: peri_26m
+            - const: top_133m
 
 unevaluatedProperties: false