enb: Add cell_list attribute

It allows configuring each cell_list up to a maximum of 'num_cells'.

Change-Id: I4fd30a3e37789b76bfaddc2beba1815154daab7f
diff --git a/sysmocom/defaults.conf b/sysmocom/defaults.conf
index f3994bb..bf5bce1 100644
--- a/sysmocom/defaults.conf
+++ b/sysmocom/defaults.conf
@@ -123,6 +123,13 @@
   a3_report_value: 6
   a3_hysteresis: 0
   a3_time_to_trigger: 480
+  cell_list:
+   - cell_id: 0x01
+     dl_earfcn: 2850
+     scell_list: [0x02]
+   - cell_id: 0x02
+     dl_earfcn: 3050
+     scell_list: [0x01]
 
 srsenb:
   num_prb: 100