mtl mxm: update configuration parsing api to mxm 2.1, drop
older version support (1.0 and 1.1), and cleanup the code.

reviewed by miked.

cmr=v1.7.4:reviewer=ompi-gk1.7
spml ikrit: update configuration parsing api to mxm 2.1, drop
older version support (1.0 and 1.1), and cleanup the code.

reviewed by miked.