pci: add kernel driver type

pci: add kernel driver type

Currently, dpdk has no ability to know which type of driver(
vfio-pci/igb_uio/uio_pci_generic) the device used. It only can
check whether vfio is enabled or not statically.

It really useful to have the flag, because different type need to
handle differently in runtime. For example, pci memory map,
pot hotplug, and so on.

This patch add a flag field for pci device to solve above issue.

Signed-off-by: Michael Qiu <michael.qiu@intel.com>
Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>