QMP: Simplify monitor_json_emitter()

Use the ternary operator instead of an if (also fixes bad indentation).
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

monitor.c

@@ -351,10 +351,8 @@ static void monitor_json_emitter(Monitor *mon, const QObject *data)
 {
     QString *json;
 
-    if (mon->flags & MONITOR_USE_PRETTY)
-	json = qobject_to_json_pretty(data);
-    else
-	json = qobject_to_json(data);
+    json = mon->flags & MONITOR_USE_PRETTY ? qobject_to_json_pretty(data) :
+                                             qobject_to_json(data);
     assert(json != NULL);
 
     qstring_append_chr(json, '\n');