FORMLIST: dt-bindings: PCI: qcom,pcie-sa8775p: document link_down reset

Each PCIe controller on sa8775p includes 'link_down'reset on hardware,
document it.

Signed-off-by: Ziyue Zhang <quic_ziyuzhan@quicinc.com>
Link: https://lore.kernel.org/all/20250625090048.624399-3-quic_ziyuzhan@quicinc.com/

Author: ziyuezhang-123

Documentation/devicetree/bindings/pci/qcom,pcie-sa8775p.yaml

@@ -59,11 +59,14 @@ properties:
       - const: msi7
 
   resets:
-    maxItems: 1
+    items:
+      - description: PCIe controller reset
+      - description: PCIe link down reset
 
   reset-names:
     items:
-      - const: pci
+      - const: pci # PCIe core reset
+      - const: link_down # PCIe link down reset
 
 required:
   - interconnects
@@ -157,8 +160,10 @@ examples:
 
             power-domains = <&gcc PCIE_0_GDSC>;
 
-            resets = <&gcc GCC_PCIE_0_BCR>;
-            reset-names = "pci";
+            resets = <&gcc GCC_PCIE_0_BCR>,
+                     <&gcc GCC_PCIE_0_LINK_DOWN_BCR>;
+            reset-names = "pci",
+                          "link_down";
 
             perst-gpios = <&tlmm 2 GPIO_ACTIVE_LOW>;
             wake-gpios = <&tlmm 0 GPIO_ACTIVE_HIGH>;