Fixes #3958: use the right type name (mca_topo_base_module_t) in the
debugger code (not mca_topo_base_module_2_1_0_t).

I checked: we do a similar thing for coll in the communicator struct
(i.e., leave the version number off the module struct).  I confess to
not remembering ''why'' we leave the version number off, but it seems
to be consistent this way...

cmr=v1.7.4:reviewer=bosilca:subject=fix debugger type symbol lookup for mca_topo_base_module_t