trace: make the trace_event callbacks return enum print_line_t

As they actually all return these enumerators.

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index f6b35e1..7ac72a4 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -160,7 +160,8 @@
 	return TRACE_TYPE_PARTIAL_LINE;
 }
 
-static int trace_branch_print(struct trace_iterator *iter, int flags)
+static enum print_line_t trace_branch_print(struct trace_iterator *iter,
+					    int flags)
 {
 	struct trace_branch *field;