dt-bindings: net: dsa: qca8k: document support for qca8328

QCA8328 is the bigger brother of qca8327. Document the new compatible
binding and add some information to understand the various switch
compatible.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/qca8k.txt

@@ -3,9 +3,10 @@
 Required properties:
 
 - compatible: should be one of:
-    "qca,qca8327"
-    "qca,qca8334"
-    "qca,qca8337"
+    "qca,qca8328": referenced as AR8328(N)-AK1(A/B) QFN 176 pin package
+    "qca,qca8327": referenced as AR8327(N)-AL1A DR-QFN 148 pin package
+    "qca,qca8334": referenced as QCA8334-AL3C QFN 88 pin package
+    "qca,qca8337": referenced as QCA8337N-AL3(B/C) DR-QFN 148 pin package
 
 - #size-cells: must be 0
 - #address-cells: must be 1