bus/pci: add Mellanox kernel driver type

bus/pci: add Mellanox kernel driver type

When checking RTE_PCI_DRV_IOVA_AS_VA flag to determine IOVA mode,
pci_one_device_has_iova_va() returns true only if kernel driver of the
device is vfio. However, Mellanox mlx4/5 PMD doesn't need to be detached
from kernel driver and attached to VFIO/UIO. Control path still goes
through the existing kernel driver, which is mlx4_core/mlx5_core. In order
to make RTE_PCI_DRV_IOVA_AS_VA effective for mlx4/mlx5 PMD, a new kernel
driver type has to be introduced.

Cc: stable@dpdk.org
Signed-off-by: Yongseok Koh <yskoh@mellanox.com>