ethdev: add VLAN and MPLS actions to flow API

ethdev: add VLAN and MPLS actions to flow API

Add support for the following OpenFlow-defined actions:

- RTE_FLOW_ACTION_OF_POP_VLAN: pop the outer VLAN tag.

- RTE_FLOW_ACTION_OF_PUSH_VLAN: push a new VLAN tag.

- RTE_FLOW_ACTION_OF_SET_VLAN_VID: set the 802.1q VLAN id.

- RTE_FLOW_ACTION_OF_SET_VLAN_PCP: set the 802.1q priority.

- RTE_FLOW_ACTION_OF_POP_MPLS: pop the outer MPLS tag.

- RTE_FLOW_ACTION_OF_PUSH_MPLS: push a new MPLS tag.

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>