srsenb: Fix ECI in handover cell list

So far we only support setting cell IDs from same ENB. Support for
handover to other ENB will come later, probably by adding some API to be
called during the test to add own's CellID's to other ENB's config.t

Change-Id: I1780bda130cde0faab15d4032117e0aa2b9c5dbe

src/osmo_gsm_tester/templates/srsenb_rr.conf.tmpl

@@ -88,7 +88,7 @@ cell_list =
         ${',' if loop.my_num_items != 0 else ''}
         <% loop.my_num_items += 1 %>
         {
-          eci = ${ncell.cell_id};
+          eci = ${hex((int(enb.id)<<8) + int(ncell.cell_id))};
           dl_earfcn = ${ncell.dl_earfcn};
           pci = ${ncell.pci};
         }