net/virtio: fix secondary process crash with PCI devices

net/virtio: fix secondary process crash with PCI devices

The Virtio rework series mistakenly moved the rte_pci_device
pointer to struct virtio_hw, which is shared between the two
processes. But this structure is per-process, so this change
made secondary process to try accessing primary process-only
memory, leading to a crash.

This patch reverts to proper behavior, by storing the
rte_pci_device pointer into the per-process
virtio_pci_internal struct. It also provides helper to get
the pointer from the virtio_hw struct pointer.

Bugzilla ID: 633
Fixes: c8d4b02f72ae ("net/virtio: move legacy IO to virtio PCI")

Reported-by: Anatoly Burakov <anatoly.burakov@intel.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>