Since vphn_enabled is always 0, we can stub out
timed_topology_update() and remove the code which becomes unreachable.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612051238.1007764-7-nathanl@linux.ibm.com