net/ifcvf: add ifcvf vDPA driver

net/ifcvf: add ifcvf vDPA driver

The IFCVF vDPA (vhost data path acceleration) driver provides support for
the Intel FPGA 100G VF (IFCVF). IFCVF's datapath is virtio ring compatible,
it works as a HW vhost backend which can send/receive packets to/from
virtio directly by DMA.

Different VF devices serve different virtio frontends which are in
different VMs, so each VF needs to have its own DMA address translation
service. During the driver probe a new container is created, with this
container vDPA driver can program DMA remapping table with the VM's memory
region information.

Key vDPA driver ops implemented:

- ifcvf_dev_config:
  Enable VF data path with virtio information provided by vhost lib,
  including IOMMU programming to enable VF DMA to VM's memory, VFIO
  interrupt setup to route HW interrupt to virtio driver, create notify
  relay thread to translate virtio driver's kick to a MMIO write onto HW,
  HW queues configuration.

- ifcvf_dev_close:
  Revoke all the setup in ifcvf_dev_config.

Live migration feature is supported by IFCVF and this driver enables
it. For the dirty page logging, VF helps to log for packet buffer write,
driver helps to make the used ring as dirty when device stops.

Because vDPA driver needs to set up MSI-X vector to interrupt the
guest, only vfio-pci is supported currently.

Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
Signed-off-by: Rosen Xu <rosen.xu@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>