perf callchain: Switch default to 'graph,0.5,caller'

Which is the most common default found in other similar tools.

Requested-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chandler Carruth <chandlerc@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://www.youtube.com/watch?v=nXaxk27zwlk
Link: http://lkml.kernel.org/n/tip-v8lq36aispvdwgxdmt9p9jd9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/util.c

@@ -17,9 +17,9 @@
 #include "callchain.h"
 
 struct callchain_param	callchain_param = {
-	.mode	= CHAIN_GRAPH_REL,
+	.mode	= CHAIN_GRAPH_ABS,
 	.min_percent = 0.5,
-	.order  = ORDER_CALLEE,
+	.order  = ORDER_CALLER,
 	.key	= CCKEY_FUNCTION
 };