panic in dmar_remove_one_dev_info

[Jerry Snitselaar]

HP is seeing a panic on gen9 dl360 and dl560 while testing these other
changes we've been eorking on. I just took an initial look, but have
to run to a dentist appointment so couldn't dig too deep. It looks
like the device sets dev->archdata.iommu to DEFER_DEVICE_DOMAIN_INFO
in intel_iommu_add_device, and then it needs a private domain so
dmar_remove_one_dev_info gets called. That code path ends up trying to
use DEFER_DEVICE_DOMAIN_INFO as a pointer.  I don't need if there just
needs to be a check in there to bail out if it sees
DEFER_DEVICE_DOMAIN_INFO, or if something more is needed. I'll look
at it some more when I get back home.

Regards,
Jerry