document vfio-pci setup for QAT 1.x devices

[mythi]

QAT 1.x are 'denylisted' in vfio-pci (a change to vfio-pci was added in Linux 5.9).

[   63.719253] vfio-pci 0000:b1:01.0: 8086:37c9 exists in vfio-pci device denylist, driver probing disallowed.
[   63.719279] vfio-pci: probe of 0000:b1:01.0 failed with error -22
[   63.745892] vfio-pci 0000:b1:01.1: 8086:37c9 exists in vfio-pci device denylist, driver probing disallowed.
[   63.745918] vfio-pci: probe of 0000:b1:01.1 failed with error -22
[   63.771618] vfio-pci 0000:b1:02.2: 8086:37c9 exists in vfio-pci device denylist, driver probing disallowed.
[   63.771643] vfio-pci: probe of 0000:b1:02.2 failed with error -22

Document how to deal with this.