BugLink: http://bugs.launchpad.net/bugs/1566221

IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO register
space. This would potentially permit root to trigger arbitrary DMA, so lock
it down by default.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>