net/mlx5e: Avoid supporting udp tunnel port ndo for VF reps

This was added to allow the TC offloading code to identify offloading
encap/decap vxlan rules.

The VF reps are effectively related to the same mlx5 PCI device as the
PF. Since the kernel invokes the (say) delete ndo for each netdev, the
FW erred on multiple vxlan dst port deletes when the port was deleted
from the system.

We fix that by keeping the registration to be carried out only by the
PF. Since the PF serves as the uplink device, the VF reps will look
up a port there and realize if they are ok to offload that.

Tested:
 <SETUP VFS>
 <SETUP switchdev mode to have representors>
 ip link add vxlan1 type vxlan id 44 dev ens5f0 dstport 9999
 ip link set vxlan1 up
 ip link del dev vxlan1

Fixes: 4a25730e ('net/mlx5e: Add ndo_udp_tunnel_add to VF representors')
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>