This new MTL runs over PSM2 for Omni Path. PSM2 is a descendant of PSM
with changes to support more ranks and some MPI-3 features like mprobe.
PSM2 will only support Omni Path networks; PSM only supports True Scale.
Likewise, the existing PSM MTL will continue to be maintained for True
Scale, while the PSM2 MTL is developed and maintained for Omni Path.
