trace: split subpage MMIOs into their own trace events.

trace: split subpage MMIOs into their own trace events.

Previously, a single MMIO could trigger the memory_region_ops tracepoint twice:
once on its way into subpage ops, then later on its way into the model's ops.

Also, the fields previously called "addr" are actually offsets into the memory
region. Rename them to "offset" while we're editing the tracepoint definitions.

Signed-off-by: Hollis Blanchard <hollis_blanchard@mentor.com>
Message-id: 1454976185-30095-2-git-send-email-hollis_blanchard@mentor.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>