sched/x86: Rewrite set_cpu_sibling_map()

sched/x86: Rewrite set_cpu_sibling_map()

Commit 3f2880bf1 ("x86/numa: Check for nonsensical topologies on real
hw as well") is broken in that the condition can trigger for valid
setups but only changes the end result for invalid setups with no real
means of discerning between those.

Rewrite set_cpu_sibling_map() to make the code clearer and make sure
to only warn when the check changes the end result.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-klcwahu3gx467uhfiqjyhdcs@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>