hw/scsi/vmw_pvscsi: Use qbus_reset_all() directly

Since the BusState is accesible from the SCSIBus object,
it is pointless to use qbus_reset_all_fn.
Use qbus_reset_all() directly.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Dmitry Fleytman <dmitry.fleytman@gmail.com>
Message-Id: <20190528164020.32250-2-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>