Move the typedef closer to the QOM type checking macros.
This will make future conversion to OBJECT_DECLARE* easier.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20200825192110.3528606-54-ehabkost@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>