enb: Add attribute to set 'id'

Change-Id: I8ce296c7875d557062dc13e7093ce0400050f2ce
diff --git a/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl b/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl
index 11704b6..89e65f1 100644
--- a/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl
+++ b/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl
@@ -51,7 +51,7 @@
   gtp_addr: "${enb.gtp_bind_addr}",
 
   /* high 20 bits of SIB1.cellIdentifier */
-  enb_id: 0x19B,
+  enb_id: ${enb.id},
 
   /* list of cells */
   cell_list: [