chan_misdn: Fix a few issues causing compile errors

Change-Id: I54b48c24d7ca88ed80496fdfd142d08772a7ab98

channels/chan_misdn.c

@@ -369,8 +369,8 @@ struct hold_info {
 	int channel;
 };
 
-#define chan_list_ref(obj, debug) (ao2_t_ref((obj), +1, (debug)), (obj))
-#define chan_list_unref(obj, debug) (ao2_t_ref((obj), -1, (debug)), NULL)
+#define chan_list_ref(obj, debug) ao2_t_ref((obj), +1, (debug))
+#define chan_list_unref(obj, debug) ao2_t_ref((obj), -1, (debug))
 
 /*!
  * \brief Channel call record structure

channels/misdn_config.c

@@ -698,7 +698,7 @@ void misdn_cfg_get_desc (enum misdn_cfg_elements elem, void *buf, int bufsize, v
 	else if ((elem > MISDN_GEN_FIRST) && (elem < MISDN_GEN_LAST))
 		spec = (struct misdn_cfg_spec *)gen_spec;
 
-	if (!spec || !spec[place].desc)
+	if (!spec)
 		memset(buf, 0, 1);
 	else {
 		ast_copy_string(buf, spec[place].desc, bufsize);