According to PnP specification, Appendix B, Option ROMs
that support DDIM (device driver initialization model) should
have their memory space writeable.
KVM deviates from us here, by removing the IO_MEM_ROM flag,
to allow for PCI option ROMs (they require DDIM). However,
there's absolutely no reason we can't do the same.
Signed-off-by: Glauber Costa <glommer@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>