dt-bindings: net: nxp,sja1105: document spi-cpol/cpha

Some boards use SJA1105 Ethernet Switch with SPI CPHA, while ones with
SJA1110 use SPI CPOL, so document this to fix dtbs_check warnings:

  arch/arm64/boot/dts/freescale/fsl-lx2160a-bluebox3.dtb: ethernet-switch@0: Unevaluated properties are not allowed ('spi-cpol' was unexpected)

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/nxp,sja1105.yaml

@@ -12,10 +12,6 @@ description:
   cs_sck_delay of 500ns. Ensuring that this SPI timing requirement is observed
   depends on the SPI bus master driver.
 
-allOf:
-  - $ref: dsa.yaml#/$defs/ethernet-ports
-  - $ref: /schemas/spi/spi-peripheral-props.yaml#
-
 maintainers:
   - Vladimir Oltean <vladimir.oltean@nxp.com>
 
@@ -36,6 +32,9 @@ properties:
   reg:
     maxItems: 1
 
+  spi-cpha: true
+  spi-cpol: true
+
   # Optional container node for the 2 internal MDIO buses of the SJA1110
   # (one for the internal 100base-T1 PHYs and the other for the single
   # 100base-TX PHY). The "reg" property does not have physical significance.
@@ -109,6 +108,30 @@ $defs:
        1860, 1880, 1900, 1920, 1940, 1960, 1980, 2000, 2020, 2040, 2060, 2080,
        2100, 2120, 2140, 2160, 2180, 2200, 2220, 2240, 2260]
 
+allOf:
+  - $ref: dsa.yaml#/$defs/ethernet-ports
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+  - if:
+      properties:
+        compatible:
+          enum:
+            - nxp,sja1105e
+            - nxp,sja1105p
+            - nxp,sja1105q
+            - nxp,sja1105r
+            - nxp,sja1105s
+            - nxp,sja1105t
+    then:
+      properties:
+        spi-cpol: false
+      required:
+        - spi-cpha
+    else:
+      properties:
+        spi-cpha: false
+      required:
+        - spi-cpol
+
 unevaluatedProperties: false
 
 examples:
@@ -120,6 +143,7 @@ examples:
             ethernet-switch@1 {
                     reg = <0x1>;
                     compatible = "nxp,sja1105t";
+                    spi-cpha;
 
                     ethernet-ports {
                             #address-cells = <1>;