net/mlx5: fix E-Switch manager vport ID

net/mlx5: fix E-Switch manager vport ID

One of the E-Switch vports plays the special role - it is assigned as
"E-Switch manager" and has some special exclusive rights and duties - it
maintains all the representors, manages FDB domain flows, etc. By
default, the E-Switch vport index was supposed to be zero on standalone
NICs (regular ConnectX) and 0xFFFE SmartNIC (BlueField), but that was
not always correct - this index can be assigned with any value by
kernel/hypervisor.

Currently the E-Switch manager vport id is supposed to be default - 0
for standalone NICs, and 0xFFFE for the SmartNICs, and is deduced from
the device PCI id.

To handle this and do not suggest any default values, can use DevX API
to query E-Switch manager vport ID directly from the firmware during
initialization, and use that value by default. If the new method is not
provided (legacy firmware), fallback to use the PCI id approach.

Fixes: a564038699f9 ("net/mlx5: support E-Switch manager egress traffic match")
Cc: stable@dpdk.org
Signed-off-by: Shun Hao <shunh@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>