dt-bindings: PCI: mediatek-gen3: Add support for MT6991/MT8196

Add compatible strings for MT8196 and MT6991 (which are fully
compatible between each other) and clock definitions.

These new SoCs don't have tl_96m and tl_32k clocks, but need
an AHB to APB bus clock and a low power clock.

Signed-off-by: AngeloGioacchino Del Regno <[email protected]>
[mani: changed 'maxItems' to 'minItems' for reset]
Signed-off-by: Manivannan Sadhasivam <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: AngeloGioacchino Del Regno

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

@@ -52,7 +52,12 @@ properties:
               - mediatek,mt8188-pcie
               - mediatek,mt8195-pcie
           - const: mediatek,mt8192-pcie
+      - items:
+          - enum:
+              - mediatek,mt6991-pcie
+          - const: mediatek,mt8196-pcie
       - const: mediatek,mt8192-pcie
+      - const: mediatek,mt8196-pcie
       - const: airoha,en7581-pcie
 
   reg:
@@ -212,6 +217,36 @@ allOf:
 
         mediatek,pbus-csr: false
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - mediatek,mt8196-pcie
+    then:
+      properties:
+        clocks:
+          minItems: 6
+
+        clock-names:
+          items:
+            - const: pl_250m
+            - const: tl_26m
+            - const: bus
+            - const: low_power
+            - const: peri_26m
+            - const: peri_mem
+
+        resets:
+          minItems: 2
+
+        reset-names:
+          items:
+            - const: phy
+            - const: mac
+
+        mediatek,pbus-csr: false
+
   - if:
       properties:
         compatible: