dt-bindings: PCI: brcm,stb-pcie: Add 7712 SoC description

Add description for the 7712 SoC, a Broadcom STB sibling chip
of the Raspberry Pi 5.

The 7712 uses three reset controllers: rescal, for PHY reset
calibration; bridge, for the bridge between the PCIe bus and
the memory bus; and swinit, which is a "soft" initialization
of the PCIe HW.

Link: https://lore.kernel.org/linux-pci/20240815225731.40276-4-james.quinlan@broadcom.com
Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml

@@ -21,6 +21,7 @@ properties:
           - brcm,bcm7425-pcie # Broadcom 7425 MIPs
           - brcm,bcm7435-pcie # Broadcom 7435 MIPs
           - brcm,bcm7445-pcie # Broadcom 7445 Arm
+          - brcm,bcm7712-pcie # Broadcom STB sibling of Rpi 5
 
   reg:
     maxItems: 1
@@ -96,10 +97,12 @@ properties:
       maxItems: 3
 
   resets:
-    maxItems: 1
+    minItems: 1
+    maxItems: 3
 
   reset-names:
-    maxItems: 1
+    minItems: 1
+    maxItems: 3
 
 required:
   - compatible
@@ -151,6 +154,27 @@ allOf:
         - resets
         - reset-names
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: brcm,bcm7712-pcie
+    then:
+      properties:
+        resets:
+          minItems: 3
+          maxItems: 3
+
+        reset-names:
+          items:
+            - const: rescal
+            - const: bridge
+            - const: swinit
+
+      required:
+        - resets
+        - reset-names
+
 unevaluatedProperties: false
 
 examples: