net: dsa: add support for ksz9897 ethernet switch

ksz9477 is superset of ksz9xx series, driver just works
out of the box for ksz9897 chip with this patch.

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/ksz.txt

@@ -4,7 +4,9 @@ Microchip KSZ Series Ethernet switches
 Required properties:
 
 - compatible: For external switch chips, compatible string must be exactly one
-  of: "microchip,ksz9477"
+  of the following:
+  - "microchip,ksz9477"
+  - "microchip,ksz9897"
 
 See Documentation/devicetree/bindings/net/dsa/dsa.txt for a list of additional
 required and optional properties.