From: Matthew Dobson <colpatch@us.ibm.com>

sched_best_cpu schedules processes on nodes based on node_nr_running.  For
CPU-less nodes, this is always 0, and thus sched_best_cpu tends to migrate
tasks to these nodes, which eventually get remigrated elsewhere.

This patch adds include/linux/topology.h, and modifies all includes of
asm/topology.h to linux/topology.h.  A subsequent patch in this series adds
helper functions to linux/topology.h to ensure processes are only migrated
to nodes with CPUs.

Test compiled and booted by Andrew Theurer (habanero@us.ibm.com) on both
x440 and ppc64.