dt-bindings: PCI: layerscape-pci: Change property 'fsl,pcie-scfg' type

The fsl,pcie-scfg requires an argument when there are more than one PCIe
instances.

Thus, change it to the phandle-array type and use items to describe
what each field means.

This also fixes the following warning:

  arch/arm64/boot/dts/freescale/fsl-ls1043a-rdb.dtb: pcie@3400000: fsl,pcie-scfg:0: [22, 0] is too long from schema $id: http://devicetree.org/schemas/pci/fsl,layerscape-pcie.yaml#

Link: https://lore.kernel.org/linux-pci/20240701221612.2112668-1-Frank.Li@nxp.com
Signed-off-by: Frank Li <Frank.Li@nxp.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>

Author: nxpfrankli

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

@@ -45,10 +45,15 @@ properties:
       - const: config
 
   fsl,pcie-scfg:
-    $ref: /schemas/types.yaml#/definitions/phandle
+    $ref: /schemas/types.yaml#/definitions/phandle-array
     description: A phandle to the SCFG device node. The second entry is the
       physical PCIe controller index starting from '0'. This is used to get
       SCFG PEXN registers.
+    items:
+      items:
+        - description: A phandle to the SCFG device node
+        - description: PCIe controller index starting from '0'
+    maxItems: 1
 
   big-endian:
     $ref: /schemas/types.yaml#/definitions/flag