dt-binding: ptp: fsl,ptp: add pci1957,ee02 compatible string for fsl,enetc-ptp

fsl,enetc-ptp is embedded pcie device. Add compatible string pci1957,ee02.

Fix warning:
arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-kbox-a-230-ls.dtb: ethernet@0,4:
	compatible:0: 'pci1957,ee02' is not one of ['fsl,etsec-ptp', 'fsl,fman-ptp-timer', 'fsl,dpaa2-ptp', 'fsl,enetc-ptp']
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/ptp/fsl,ptp.yaml

@@ -11,11 +11,14 @@ maintainers:
 
 properties:
   compatible:
-    enum:
-      - fsl,etsec-ptp
-      - fsl,fman-ptp-timer
-      - fsl,dpaa2-ptp
-      - fsl,enetc-ptp
+    oneOf:
+      - enum:
+          - fsl,etsec-ptp
+          - fsl,fman-ptp-timer
+          - fsl,dpaa2-ptp
+      - items:
+          - const: pci1957,ee02
+          - const: fsl,enetc-ptp
 
   reg:
     maxItems: 1
@@ -123,6 +126,15 @@ required:
   - compatible
   - reg
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: fsl,enetc-ptp
+    then:
+      $ref: /schemas/pci/pci-device.yaml
+
 additionalProperties: false
 
 examples: