tracing: remove extra latency_trace method from trace structure

Impact: clean up

The trace and latency_trace function pointers are identical for
every tracer but the function tracer. The differences in the function
tracer are trivial (latency output puts paranthesis around parent).

This patch removes the latency_trace pointer and all prints will
now just use the trace output function pointer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

kernel/trace/trace.c

@@ -1485,7 +1485,7 @@ static enum print_line_t print_lat_fmt(struct trace_iterator *iter)
 	}
 
 	if (event)
-		return event->latency_trace(iter, sym_flags);
+		return event->trace(iter, sym_flags);
 
 	if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
 		goto partial;