vfio/igd: emulate BDSM in mmio bar0 for gen 6-10 devices

vfio/igd: emulate BDSM in mmio bar0 for gen 6-10 devices

A recent commit in i915 driver [1] claims the BDSM register at 0x1080c0
of mmio bar0 has been there since gen 6. Mirror this register to the 32
bit BDSM register at 0x5c in pci config space for gen6-10 devices.

[1] https://patchwork.freedesktop.org/patch/msgid/20240202224340.30647-7-ville.syrjala@linux.intel.com

Reviewed-by: Corvin Köhne <c.koehne@beckhoff.com>
Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20241206122749.9893-10-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>