dt-bindings: PCI: fsl,imx6q-pcie: Add reset GPIO in Root Port node

Update fsl,imx6q-pcie.yaml to include the standard reset-gpios property for
the Root Port node.

The reset-gpios property is already defined in pci-bus-common.yaml for
PERST#, so use it instead of the local reset-gpio property. Keep the
existing reset-gpio property in the bridge node for backward compatibility,
but mark it as deprecated.

Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260422093549.407022-2-sherry.sun@nxp.com

Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml

@@ -66,16 +66,34 @@ properties:
       - const: dma
 
   reset-gpio:
+    deprecated: true
     description: Should specify the GPIO for controlling the PCI bus device
       reset signal. It's not polarity aware and defaults to active-low reset
       sequence (L=reset state, H=operation state) (optional required).
+      This property is deprecated, instead of referencing this property from the
+      host bridge node, use the reset-gpios property from the root port node.
 
   reset-gpio-active-high:
+    deprecated: true
     description: If present then the reset sequence using the GPIO
       specified in the "reset-gpio" property is reversed (H=reset state,
       L=operation state) (optional required).
+      This property is deprecated along with the reset-gpio property above, use
+      the reset-gpios property from the root port node.
     type: boolean
 
+  pcie@0:
+    description:
+      Describe the i.MX6 PCIe Root Port.
+    type: object
+    $ref: /schemas/pci/pci-pci-bridge.yaml#
+
+    properties:
+      reg:
+        maxItems: 1
+
+    unevaluatedProperties: false
+
 required:
   - compatible
   - reg
@@ -236,6 +254,7 @@ unevaluatedProperties: false
 examples:
   - |
     #include <dt-bindings/clock/imx6qdl-clock.h>
+    #include <dt-bindings/gpio/gpio.h>
     #include <dt-bindings/interrupt-controller/arm-gic.h>
 
     pcie: pcie@1ffc000 {
@@ -262,5 +281,18 @@ examples:
                 <&clks IMX6QDL_CLK_LVDS1_GATE>,
                 <&clks IMX6QDL_CLK_PCIE_REF_125M>;
         clock-names = "pcie", "pcie_bus", "pcie_phy";
+
+        pcie_port0: pcie@0 {
+            compatible = "pciclass,0604";
+            device_type = "pci";
+            reg = <0x0 0x0 0x0 0x0 0x0>;
+            bus-range = <0x01 0xff>;
+
+            #address-cells = <3>;
+            #size-cells = <2>;
+            ranges;
+
+            reset-gpios = <&gpio7 12 GPIO_ACTIVE_LOW>;
+        };
     };
 ...