The existing "fallback" code didn't actually do anything, so this
removes it, and instead we just always fallback to `iris` for future
PCI IDs.
Suggested-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>