board/netconf: Define standard behavior for port LEDs

By default, assume that any LED with the function "tp", "sfp" or
"port" is attached to either an Ethernet PHY or MAC, with support for
offloading the "netdev" trigger.

Use green LEDs to indicate link/activity.

Disable any yellow LEDs for now, later on we can add alarm indications
etc. to these.

board/netconf/rootfs/etc/iitod.json

@@ -29,6 +29,21 @@
     },
 
     "output": {
+	"led-group": {
+	    "port-link-act": {
+		"match": ["*:green:tp", "*:green:sfp", "*:green:port" ],
+
+		"rules": [
+		    { "if": "true", "then": { "trigger": "netdev", "link": 1, "rx": 1, "tx": 1 } }
+		]
+	    },
+	    "port-alarm": {
+		"match": ["*:yellow:tp", "*:yellow:sfp", "*:yellow:port" ],
+
+		"rules": [
+		]
+	    }
+	},
 	"led": {
 	    "red:status": {
 		"rules": [