gsm: constify several readonly params
Change-Id: Ib11bfe57f546a5618f70152b9b75115808e54bf6
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index 30bba91..c5fe550 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -1361,7 +1361,7 @@
* Uses From Table 10.5.33 of GSM 04.08 to determine the number of
* paging sub-channels in the given control channel configuration
*/
-int gsm48_number_of_paging_subchannels(struct gsm48_control_channel_descr *chan_desc)
+int gsm48_number_of_paging_subchannels(const struct gsm48_control_channel_descr *chan_desc)
{
unsigned int n_pag_blocks = gsm0502_get_n_pag_blocks(chan_desc);