net/mlx5: fix switchdev mode recognition

net/mlx5: fix switchdev mode recognition

The new kernels might add the switch_id attribute to the
Netlink replies and this caused the wrong recognition
of the E-Switch presence. The single uplink device was
erroneously recognized as master and it caused the
extending match for source vport index on all installed
flows, including the default ones, and adding extra hops
in the steering engine, that affected the maximal
throughput packet rate.

The extra check for the new device name format (it supposes
the new kernel) and the device is only one is added. If this
check succeeds the E-Switch presence is considered as wrongly
detected and overridden.

Fixes: 30a86157f6d5 ("net/mlx5: support PF representor")
Cc: stable@dpdk.org
Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>