fix a warning in openair3/NAS/UE/EMM/IdleMode.c

I'm not sure this is the right fix, so I put a LOG_TRACE
that is displayed when the code comes here.

openair3/NAS/UE/EMM/IdleMode.c

@@ -903,7 +903,10 @@ int emm_proc_plmn_selection_end(int found, tac_t tac, ci_t ci, AcT_t rat)
    * Or terminate the PLMN selection procedure
    */
   if (!select_next_plmn) {
-    if (!(_emm_plmn_list.fplmn) < 0) { // FIXME this comparison makes no sense (bool < 0)
+    /* TODO: be sure of this fix */
+    LOG_TRACE(WARNING, "%s:%d:%s: be sure!!\n", __FILE__, __LINE__, __FUNCTION__);
+    //if (!(_emm_plmn_list.fplmn) < 0) { // FIXME this comparison makes no sense (bool < 0)
+    if (!(_emm_plmn_list.fplmn < 0)) { // FIXME this comparison makes no sense (bool < 0)
       /* There were one or more PLMNs which were available and allowable,
        * but an LR failure made registration on those PLMNs unsuccessful
        * or an entry in any of the forbidden area lists prevented a