fix: extract source from imm request fields instead from depricated api

This commit was SVN r25812.

ompi/mca/mtl/mxm/mtl_mxm_probe.c

@@ -30,7 +30,7 @@ int ompi_mtl_mxm_iprobe(struct mca_mtl_base_module_t* mtl,
     if (MXM_OK == err) {
         *flag = 1;
         if (MPI_STATUS_IGNORE != status) {
-            status->MPI_SOURCE = *(int *)mxm_conn_get_context(req.base.conn);
+            status->MPI_SOURCE = req.completion.sender_imm;
             status->MPI_TAG    = req.completion.sender_tag;
             status->MPI_ERROR  = ompi_mtl_mxm_to_mpi_status(err);
             status->_ucount    = req.completion.actual_len;