SRSENB: Set default PRACH sequence root index in SIB2

srsenb/src/stack/rrc/rrc.cc

@@ -71,6 +71,9 @@ void rrc::init(rrc_cfg_t*             cfg_,
     configure_mbsfn_sibs(&cfg.sibs[1].sib2(), &cfg.sibs[12].sib13_v920());
   }
 
+  // Loads the PRACH root sequence
+  cfg.sibs[1].sib2().rr_cfg_common.prach_cfg.root_seq_idx = cfg.cell_list[0].root_seq_idx;
+
   nof_si_messages = generate_sibs();
   config_mac();
   enb_mobility_cfg.reset(new mobility_cfg(&cfg, log_rrc));