tools: perf: add perf-periodic

Add the 'periodic' command to perf. This allows collection
of counters at a specified interval.

Change-Id: I4e42ac3f21cbdf2c196dbd01d31e6dc6051efd7e
Signed-off-by: Neil Leeder <nleeder@codeaurora.org>
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index ec635b7..32f6673 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -320,6 +320,7 @@
 		{ "report",	cmd_report,	0 },
 		{ "bench",	cmd_bench,	0 },
 		{ "stat",	cmd_stat,	0 },
+		{ "periodic",   cmd_periodic,   0 },
 		{ "timechart",	cmd_timechart,	0 },
 		{ "top",	cmd_top,	0 },
 		{ "annotate",	cmd_annotate,	0 },