net/mlx5: add wire vport hint

net/mlx5: add wire vport hint

The kernel can use two approaches to distinguish the E-Switch
source vport in the packet metadata - either with dedicated
source_port field or register C0. To eliminate the extra source
vport matching in the hardware the source_port field can be
set to specific values (0xFFFF) for the wire source port.

This match can be applied to recognize wire port only in FDB
domain. Missing the register C0 match in the NIC Rx domain causes
incorrect representor steering within shared IB device ports
and must be always specified (if kernel uses this approach).

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>