The e500 PCI controller isn't qdev'ified yet. This leads to severe issues
when running with -drive.

To be able to use a virtio disk with an e500 VM, let's convert the PCI
controller over to qdev.
Reviewed-by: NPaul Brook <paul@codesourcery.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>