net/netvsc: fix VF support with secondary process

net/netvsc: fix VF support with secondary process

The VF device management in netvsc was using a pointer to the
rte_eth_devices. But the actual rte_eth_devices array is likely to
be place in the secondary process; which causes a crash.

The solution is to record the port of the VF (instead of a pointer)
and find the device in the per process array as needed.

Fixes: dc7680e8597c ("net/netvsc: support integrated VF")
Cc: stable@dpdk.org
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>