powerpc32: Remove useless/wrong MMU:setio progress message

Commit 77116849 ("[POWERPC] Remove unused machine call outs")
removed the call to setup_io_mappings(), so remove the associated
progress line message

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>