trace: split out trace events for io/ directory

Move all trace-events for files in the io/ directory to
their own file.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1466066426-16657-5-git-send-email-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Makefile.objs

@@ -121,3 +121,4 @@ ivshmem-server-obj-y = contrib/ivshmem-server/
 trace-events-y = trace-events
 trace-events-y += util/trace-events
 trace-events-y += crypto/trace-events
+trace-events-y += io/trace-events