higher priority than rdma and default to psm2.
Context: the Intel Omni-path driver (hfi1) has verbs support, so the openib
btl is available to use. However, at a bad performance. Without this
change osc rdma using btl openib is the default choice when running on Intel
Omni-path, with a lower performance than osc pt2pt over mtl psm2.
Signed-off-by: Matias A Cabral <matias.a.cabral@intel.com>