system_information: publicly declare generate_cell_chan_list()

Change-Id: Idc7a9ed558ed6897e15a0f6d3c23418db7cee0d0
diff --git a/include/osmocom/bsc/system_information.h b/include/osmocom/bsc/system_information.h
index 29f639d..35892d9 100644
--- a/include/osmocom/bsc/system_information.h
+++ b/include/osmocom/bsc/system_information.h
@@ -7,6 +7,7 @@
 
 struct gsm_bts;
 
+int generate_cell_chan_list(uint8_t *chan_list, struct gsm_bts *bts);
 int gsm_generate_si(struct gsm_bts *bts, enum osmo_sysinfo_type type);
 size_t si2q_earfcn_count(const struct osmo_earfcn_si2q *e);
 unsigned range1024_p(unsigned n);