Per the article at
https://community.mellanox.com/s/article/howto-change-port-type-in-mellanox-connectx-3-adapter
it should be possible to force the port type of a Mellanox VPI adapter to
infiniband or ethernet by adding a line with the PCI address and the desired
port types. However this is ignored.

After some digging, it seems that this is supposed to work by hooking the
module load in /etc/modprobe.d/50-libmlx4.conf. It attempts to run a script at
/usr/lib/mlx4-setup.sh. However, that script does not exist. The rdma-core
package instead installs it at /usr/libexec/mlx4-setup.sh.

Steps to reproduce:
- Have a Mellanox VPI card supported by the mlx4 driver (dual-personality
infiniband/ethernet)
- Set the ports to eth in the /etc/rdma/mlx4.conf, eg: "0000:27:00.0 eth eth"
- Reboot

Expected result:
- Ports should be ethernet type

Actual result:
- Ports are infiniband type