Improve mailbox message handling

Introduce a 32b magic for each message. Verify the magic for
all incoming messages.

Add reset function - in case of protocol error, effectively
reset/empty the incoming queue.

Add an error message type and message

Add version request/response

Verify payload length of responses (when applicable)

Change-Id: I8aadd4012024492533d52e2cdb38630fce5c36e2
diff --git a/utils/inference_runner/inference_runner.cpp b/utils/inference_runner/inference_runner.cpp
index b9707a9..e8e6ec8 100644
--- a/utils/inference_runner/inference_runner.cpp
+++ b/utils/inference_runner/inference_runner.cpp
@@ -206,8 +206,8 @@
     try {
         Device device;
 
-        cout << "Send ping" << endl;
-        device.ioctl(ETHOSU_IOCTL_PING);
+        cout << "Send version request" << endl;
+        device.ioctl(ETHOSU_IOCTL_VERSION_REQ);
 
         /* Create network */
         cout << "Create network" << endl;