[FIX] correct inventory when moves exist with and without lots

Fixes https://bugs.launchpad.net/openobject-addons/+bug/1008099
This was fixed as part of OPW in v6.0 and v6.1 but was never ported to trunk or v7.0.
When filling the inventory line with product and does not provide production lot then totol qty
should return qty withouht production lot(prodlot_id==Null) but currently it does not distinguish
and retund all qty with and without lot. It leads to wrong creation of stock moves.