Fixed ChassisId constrcutor to allow 64-bit hex strings as a parameter.

Change-Id: Ief27b2c30fc3569f5907b7d23040bf483c89f04d
diff --git a/utils/misc/src/main/java/org/onlab/packet/ChassisId.java b/utils/misc/src/main/java/org/onlab/packet/ChassisId.java
index c72713d..2d53ab8 100644
--- a/utils/misc/src/main/java/org/onlab/packet/ChassisId.java
+++ b/utils/misc/src/main/java/org/onlab/packet/ChassisId.java
@@ -47,7 +47,7 @@
      * @param value the value to use.
      */
     public ChassisId(String value) {
-        super(Long.parseLong(value, 16));
+        super(Long.parseUnsignedLong(value, 16));
     }
 
     /**