Enable checkstyle rule for missing defaults in switch statements

Enabled the checkstyle rule that looks for switch statements that
don't have a default label and fixed the violations that were
found.

Code review results for switch statement default branches

Change-Id: I68716894952835def659b4fcab5b381aaf9ff89e
diff --git a/src/main/java/net/onrc/onos/core/packet/DHCPPacketType.java b/src/main/java/net/onrc/onos/core/packet/DHCPPacketType.java
index 7c4cdb8..eb43d34 100644
--- a/src/main/java/net/onrc/onos/core/packet/DHCPPacketType.java
+++ b/src/main/java/net/onrc/onos/core/packet/DHCPPacketType.java
@@ -77,9 +77,9 @@
                 return "DHCPLEASEUNKNOWN";
             case 13:
                 return "DHCPLEASEACTIVE";
+            default:
+                return "DHCP_UnknownType(" + value + ")";
         }
-
-        return "DHCP_UnknownType(" + value + ")";
     }
 
     public static DHCPPacketType getType(int value) {
@@ -110,8 +110,8 @@
                 return DHCPLEASEUNKNOWN;
             case 13:
                 return DHCPLEASEACTIVE;
+            default:
+                return null;
         }
-
-        return null;
     }
 }