Fix some compilation warnings.

Change-Id: I7d9b28ac32ac84e3ed6ab2255e1db6245be14c77
diff --git a/src/main/java/net/onrc/onos/core/packet/DHCP.java b/src/main/java/net/onrc/onos/core/packet/DHCP.java
index 82ba850..77842ae 100644
--- a/src/main/java/net/onrc/onos/core/packet/DHCP.java
+++ b/src/main/java/net/onrc/onos/core/packet/DHCP.java
@@ -368,7 +368,7 @@
             if (code == 0 || code == 255) {
                 optionsLength += 1;
             } else {
-                optionsLength += 2 + (int) (0xff & option.getLength());
+                optionsLength += 2 + (0xff & option.getLength());
             }
         }
         int optionsPadLength = 0;