make scsi_done set ITSDONE on the xs. this means hba drivers dont have to do it (but doesnt preclude them using it internally).
make scsi_done set ITSDONE on the xs. this means hba drivers dont have to
do it (but doesnt preclude them using it internally).

discussed with krw@ miod@ and deraadt@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars