perf_counter tools: cut down default count for cpu-cycles

In my system, it takes kerneltop dozens of minutes to
show up usable numbers. Make the default count 100 times
smaller fixed this long startup latency.

I'm not sure if it's the right solution though.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>