block: use bdrv_co_refresh_total_sectors when possible

In some places we are sure we are always running in a
coroutine, therefore it's useless to call the generated_co_wrapper,
instead call directly the _co_ function.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230113204212.359076-9-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>