dt-bindings: phy: sparx5: document lan969x

Lan969x is going to reuse the existing Sparx5 SERDES driver - document
that by adding compatible strings for the different SKU's that we
support, and a short description of the SERDES types and data rates
supported.

Signed-off-by: Daniel Machon <[e-mail]>
Reviewed-by: Steen Hegelund <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/phy/microchip,sparx5-serdes.yaml

···
 
 maintainers:
   - Steen Hegelund <[e-mail]>
+  - Daniel Machon <[e-mail]>
 
 description: |
   The Sparx5 SERDES interfaces share the same basic functionality, but
···
   * 10.3125 Gbps (10GBASE-R/10GBASE-KR/USXGMII)
   * 25.78125 Gbps (25GBASE-KR/25GBASE-CR/25GBASE-SR/25GBASE-LR/25GBASE-ER)
 
+  lan969x has ten SERDES10G interfaces that share the same features, operating
+  modes and data rates as the equivalent Sparx5 SERDES10G interfaces.
+
 properties:
   $nodename:
     pattern: "^serdes@[0-9a-f]+$"
 
   compatible:
-    const: microchip,sparx5-serdes
+    oneOf:
+      - enum:
+          - microchip,sparx5-serdes
+          - microchip,lan9691-serdes
+      - items:
+          - enum:
+              - microchip,lan9698-serdes
+              - microchip,lan9696-serdes
+              - microchip,lan9694-serdes
+              - microchip,lan9693-serdes
+              - microchip,lan9692-serdes
+          - const: microchip,lan9691-serdes
 
   reg:
     minItems: 1