hmp: re-enable trace-file command

Commit 31965ae27bc11e90674be12584bb201b83df5aef reverted a previous
renaming of CONFIG_SIMPLE_TRACE->CONFIG_TRACE_SIMPLE in a couple spots,
leading to trace-file currently being unavailable.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/monitor.c b/monitor.c
index d323ea5..08f6197 100644
--- a/monitor.c
+++ b/monitor.c
@@ -606,7 +606,7 @@
     }
 }
 
-#ifdef CONFIG_SIMPLE_TRACE
+#ifdef CONFIG_TRACE_SIMPLE
 static void do_trace_file(Monitor *mon, const QDict *qdict)
 {
     const char *op = qdict_get_try_str(qdict, "op");