lsi: use qdev_reset_all

By first resetting the devices, lsi_soft_reset will find the queue
already cleared so there is no need to do that forcibly (which may also
leak SCSIRequests, and/or worse due to dangling references to the
lsi_request in the hba_private field).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
