perf report: No need to have report_callchain_help as a global

It is used in a single place, move the declaration to that function.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-p650ofrl8xike4dewxod51gg@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -946,12 +946,6 @@ parse_percent_limit(const struct option *opt, const char *str,
 	return 0;
 }
 
-#define CALLCHAIN_DEFAULT_OPT  "graph,0.5,caller,function,percent"
-
-const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n"
-				     CALLCHAIN_REPORT_HELP
-				     "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT;
-
 int cmd_report(int argc, const char **argv)
 {
 	struct perf_session *session;
@@ -960,6 +954,10 @@ int cmd_report(int argc, const char **argv)
 	bool has_br_stack = false;
 	int branch_mode = -1;
 	bool branch_call_mode = false;
+#define CALLCHAIN_DEFAULT_OPT  "graph,0.5,caller,function,percent"
+	const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n"
+					     CALLCHAIN_REPORT_HELP
+					     "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT;
 	char callchain_default_opt[] = CALLCHAIN_DEFAULT_OPT;
 	const char * const report_usage[] = {
 		"perf report [<options>]",