perf tools: Fix spelling mistake in callchain error

While running perf report -g in a perf.data file that hasn't
been recorded in callchain mode, the error reported has a
spelling issue:

	./perf report -g
	selected -c but no callchain data. Did you call perf record without -g?

Fix it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1250543271-8383-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-report.c

@@ -1401,7 +1401,7 @@ static int __cmd_report(void)
 			exit(-1);
 		}
 		if (callchain) {
-			fprintf(stderr, "selected -c but no callchain data."
+			fprintf(stderr, "selected -g but no callchain data."
 					" Did you call perf record without"
 					" -g?\n");
 			exit(-1);