lib/discovery/global: fix query on ifc name

In a global advertisement, the interface is encoded as a name element.
When we generate the glob pattern for a specific interface name, that
interface name must also be encoded as a name element.

Change-Id: Ie8b7045f69fd2aadb381c9c526e0aacbb07ddaeb
diff --git a/lib/discovery/global/scan.go b/lib/discovery/global/scan.go
index ddbaf23..650ee45 100644
--- a/lib/discovery/global/scan.go
+++ b/lib/discovery/global/scan.go
@@ -103,7 +103,7 @@
 		id = targetKey
 	}
 	if targetInterface := matcher.TargetInterfaceName(); targetInterface != "" {
-		interfaceName = targetInterface
+		interfaceName = naming.EncodeAsNameElement(targetInterface)
 	}
 	return naming.Join(id, interfaceName, timestamp, attrs)
 }