While we're at it, add a g_free() for the async_cmd_region that
is the last thing currently created.  g_free() knows how to handle
NULL pointers, so this makes it easier to remember what cleanups
need to be performed when new regions are added.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200505125757.98209-3-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>