perf bench numa: Fix assertion for nodes bitfield

Comparing bits and bytes in numa benchmark assertion

I hit the issue on two socket Power8 machine presenting its numa nodes
as 0,1,16,17 (according to numactl). Therefore I got error (and hang of
parent process):

    perf: bench/numa.c:296: bind_to_memnode: Assertion `!(g->p.nr_nodes > (int)sizeof(nodemask))' failed.

This is obviously false positive. We can fit all the 18 nodes into
bitfield of 8 bytes (long on 64b architecture).

Signed-off-by: Jakub Jelen <jakuje@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jakub Jelen <jjelen@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: trivial@kernel.org
Link: http://lkml.kernel.org/r/1458388687-24421-1-git-send-email-jakuje@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/bench/numa.c

@@ -293,7 +293,7 @@ static void bind_to_memnode(int node)
 	if (node == -1)
 		return;
 
-	BUG_ON(g->p.nr_nodes > (int)sizeof(nodemask));
+	BUG_ON(g->p.nr_nodes > (int)sizeof(nodemask)*8);
 	nodemask = 1L << node;
 
 	ret = set_mempolicy(MPOL_BIND, &nodemask, sizeof(nodemask)*8);