gnb,rrc: inverse order of configuring lower layers when establishing bearer

start with lower layers first, so MAC, RLC then PDCP.
Since PDCP requires that the LCID is already registered at RLC to make config
checks. It checks for RLC mode (UM) in this case causing log entries like:

2021-12-01T13:47:40.453641 [RLC-NR ] [W] LCID 4 doesn't exist.

srsgnb/src/stack/rrc/rrc_nr_ue.cc

@@ -1073,14 +1073,14 @@ void rrc_nr::ue::send_rrc_reconfiguration()
     }
 
     // Update lower layers
-    // add PDCP bearers
-    update_pdcp_bearers(ies.radio_bearer_cfg, master_cell_group);
+    // add MAC bearers
+    update_mac(master_cell_group, false);
 
     // add RLC bearers
     update_rlc_bearers(master_cell_group);
 
-    // add MAC bearers
-    update_mac(master_cell_group, false);
+    // add PDCP bearers
+    update_pdcp_bearers(ies.radio_bearer_cfg, master_cell_group);
   }
 
   if (nas_pdu_queue.size() > 0) {