Cache clean message queue

If the data cache is enabled before the queue constructor is called,
then the queue must be cleaned.

Change-Id: I29ec2b40c225065c24dc7574275482117e88cff8
diff --git a/applications/message_process/src/message_process.cc b/applications/message_process/src/message_process.cc
index dfeb830..9c0fc84 100644
--- a/applications/message_process/src/message_process.cc
+++ b/applications/message_process/src/message_process.cc
@@ -30,7 +30,9 @@
 
 namespace MessageProcess {
 
-QueueImpl::QueueImpl(ethosu_core_queue &_queue) : queue(_queue) {}
+QueueImpl::QueueImpl(ethosu_core_queue &_queue) : queue(_queue) {
+    cleanHeaderData();
+}
 
 bool QueueImpl::empty() const {
     return queue.header.read == queue.header.write;