By default the QEMU ppce500 machine connects a VirtIO NET to the
PCI controller, although it can be replaced to an e1000 NIC via
additional command line options.

Now that we have switched over to DM PCI, VirtIO support becomes
possible. This commit enables the support.
Signed-off-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NPriyanka Jain <priyanka.jain@nxp.com>