sPAPR: Enable EEH on VFIO PCI device only

This checks if the PCI device retrieved from the PCI device address
is VFIO PCI device when enabling EEH functionality. If it's not
VFIO PCI device, the EEH functonality isn't enabled.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
