nr,sched: fix sched_args_t default values

srsenb/enb.conf.example

@@ -186,8 +186,8 @@ enable = false
 # init_dl_cqi:       DL CQI value used before any CQI report is available to the eNB
 # max_sib_coderate:  Upper bound on SIB and RAR grants coderate
 # pdcch_cqi_offset:  CQI offset in derivation of PDCCH aggregation level
-# pdsch_mcs:         Optional fixed NR PDSCH MCS (ignores reported CQIs if specified)
-# pusch_mcs:         Optional fixed NR PUSCH MCS (ignores reported CQIs if specified)
+# nr_pdsch_mcs:      Optional fixed NR PDSCH MCS (ignores reported CQIs if specified)
+# nr_pusch_mcs:      Optional fixed NR PUSCH MCS (ignores reported CQIs if specified)
 #
 #####################################################################
 [scheduler]

srsenb/hdr/stack/mac/nr/sched_nr_interface.h

@@ -71,8 +71,8 @@ public:
     bool        pdsch_enabled      = true;
     bool        pusch_enabled      = true;
     bool        auto_refill_buffer = false;
-    int         fixed_dl_mcs       = -1;
-    int         fixed_ul_mcs       = -1;
+    int         fixed_dl_mcs       = 28;
+    int         fixed_ul_mcs       = 28;
     std::string logger_name        = "MAC-NR";
   };