On cards where there's a specific BAR for PRAMIN, we used to try and fall
back to the "legacy" aperture within the mmio BAR.

This is doomed to cause problems, so lets just fail completely as there's
obviously something else very wrong anyway.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>