fix 'unable to translate flow rule' in p4-tutorial icmpdropper

Change-Id: I6dbcc19f33d0db56cfce1d81c992e5592e82cf8a
diff --git a/apps/p4-tutorial/icmpdropper/src/main/java/org/onosproject/p4tutorial/icmpdropper/IcmpDropper.java b/apps/p4-tutorial/icmpdropper/src/main/java/org/onosproject/p4tutorial/icmpdropper/IcmpDropper.java
index e1f54f6..ce1c682 100644
--- a/apps/p4-tutorial/icmpdropper/src/main/java/org/onosproject/p4tutorial/icmpdropper/IcmpDropper.java
+++ b/apps/p4-tutorial/icmpdropper/src/main/java/org/onosproject/p4tutorial/icmpdropper/IcmpDropper.java
@@ -116,7 +116,7 @@
     }
 
     private void installDropRule(DeviceId deviceId) {
-        PiMatchFieldId ipv4ProtoFieldId = PiMatchFieldId.of("ipv4.protocol");
+        PiMatchFieldId ipv4ProtoFieldId = PiMatchFieldId.of("hdr.ipv4.protocol");
         PiActionId dropActionId = PiActionId.of("_drop");
 
         PiCriterion piCriterion = PiCriterion.builder()