perf bench numa: Fix cpu0 binding

Michael reported an issue with perf bench numa failing with binding to
cpu0 with '-0' option.

  # perf bench numa mem -p 3 -t 1 -P 512 -s 100 -zZcm0 --thp 1 -M 1 -ddd
  # Running 'numa/mem' benchmark:

   # Running main, "perf bench numa numa-mem -p 3 -t 1 -P 512 -s 100 -zZcm0 --thp 1 -M 1 -ddd"
  binding to node 0, mask: 0000000000000001 => -1
  perf: bench/numa.c:356: bind_to_memnode: Assertion `!(ret)' failed.
  Aborted (core dumped)

This happens when the cpu0 is not part of node0, which is the benchmark
assumption and we can see that's not the case for some powerpc servers.

Using correct node for cpu0 binding.

Reported-by: Michael Petlan <mpetlan@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20190801142642.28004-1-jolsa@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>