mbuf: add new Rx flags for stripped VLAN

mbuf: add new Rx flags for stripped VLAN

The behavior of PKT_RX_VLAN_PKT was not very well defined, resulting in
PMDs not advertising the same flags in similar conditions.

Following discussion in [1], introduce 2 new flags PKT_RX_VLAN_STRIPPED
and PKT_RX_QINQ_STRIPPED that are better defined:

  PKT_RX_VLAN_STRIPPED: a vlan has been stripped by the hardware and its
  tci is saved in mbuf->vlan_tci. This can only happen if vlan stripping
  is enabled in the RX configuration of the PMD.

For now, the old flag PKT_RX_VLAN_PKT is kept but marked as deprecated.
It should be removed from applications and PMDs in a future revision.

This patch also updates the drivers. For PKT_RX_VLAN_PKT:

- e1000, enic, i40e, mlx5, nfp, vmxnet3: done, PKT_RX_VLAN_PKT already
  had the same meaning than PKT_RX_VLAN_STRIPPED, minor update is
  required.
- fm10k: done, PKT_RX_VLAN_PKT already had the same meaning than
  PKT_RX_VLAN_STRIPPED, and vlan stripping is always enabled on fm10k.
- ixgbe: modification done (vector and normal), the old flag was set
  when a vlan was recognized, even if vlan stripping was disabled.
- the other drivers do not support vlan stripping.

For PKT_RX_QINQ_PKT, it was only supported on i40e, and the behavior was
already correct, so we can reuse the same bit value for
PKT_RX_QINQ_STRIPPED.

[1] http://dpdk.org/ml/archives/dev/2016-April/037837.html,

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>