MXM: update min required version for mxm as 2.1+

This commit was SVN r32193.
(cherry picked from commit 1b51e472ac88061572bdb4fec7528b5ad3654f49)

open-mpi/ompi@1b51e472ac88061572bdb4fec7528b5ad3654f49
reviewed by miked.
@miked-mellanox @jladd-mlnx