Do not blindly free completed ATIOs/INOTs on invalidation.

When LUN is disabled, SIM starts returning queued ATIOs/INOTs. But at the
same time there can be some ATIOs/INOTs still carrying real new requests.
If we free those, SIM may leak some resources, forever expecting for any
response from us. So try to be careful, separating ATIOs/INOTs carrying
requests which still must be processed, from ATIOs/INOTs completed with
errors which can be freed.

MFC after: 2 weeks