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.c b/kernel/trace/trace.c
index 5822ff4..fd51cf0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1495,7 +1495,7 @@
 
 	event = ftrace_find_event(entry->type);
 	if (event && event->hex) {
-		int ret = event->hex(iter, 0);
+		enum print_line_t ret = event->hex(iter, 0);
 		if (ret != TRACE_TYPE_HANDLED)
 			return ret;
 	}