powerpc/numa: remove timed_topology_update()

timed_topology_update is a no-op now, so remove it and all call sites.

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/20200612051238.1007764-11-nathanl@linux.ibm.com