While printing out the visual representation of the sched-domains, print
the level (MC, SMT, CPU, NODE, ... ) of each of the sched_domains.

Credit: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>