MPI_T_pvar_get_index was returning an incorrect index. The index
was never set correctly while registering the performance variables.
Additionally fix a missing case in the mca_base_var_type_t to MPI
datatype conversion. This type is currently used for control variables
registered by mxm, fca and hcoll components.
Signed-off-by: Nysal Jan K.A <jnysal@in.ibm.com>