Blackfin: update ftrace_push_return_trace() breakage

Commit 71e308a2 updated ftrace_push_return_trace() prototype but didn't
update the Blackfin ftrace code, so things broke.  Since we don't support
the new stuff yet, call it with stub values.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/ftrace.c

@@ -24,7 +24,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
 
-	if (ftrace_push_return_trace(*parent, self_addr, &trace.depth) == -EBUSY)
+	if (ftrace_push_return_trace(*parent, self_addr, &trace.depth, 0) == -EBUSY)
 		return;
 
 	trace.func = self_addr;