net/netvsc: support integrated VF

net/netvsc: support integrated VF

Integrate accelerated networking support into netvsc PMD.
This allows netvsc to manage VF without using failsafe or vdev_netvsc.
For the exception vswitch path some tests like transmit
get a 22% increase in packets/sec.
For the VF path, the code is slightly shorter but has no
real change in performance.

Pro:
   * using netvsc is more like other DPDK NIC's
   * the exception packet uses less CPU
   * much smaller code size
   * no locking required on VF transmit/receive path
   * no legacy Linux network device to get mangled by userspace
   * much simpler (1K vs 9K) LOC
   * unified extended statistics

Con:
   * using netvsc has more complex startup model
   * no bifurcated driver support
   * no flow support (since host does not have flow API).
   * no tunnel offload support
   * no receive interrupt support

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>