gsm/gsm48.h: drop meaningless 'const' from gsm48_mi_to_string()

Change-Id: I5eb17edadf89ac47b4ca86c9e822037f7c0e518e
diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 786fbc9..7c68b1d 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -53,8 +53,7 @@
 uint8_t gsm48_generate_mid(uint8_t *buf, const char *id, uint8_t mi_type);
 
 /* Convert Mobile Identity (10.5.1.4) to string */
-int gsm48_mi_to_string(char *string, const int str_len,
-			const uint8_t *mi, const int mi_len);
+int gsm48_mi_to_string(char *string, int str_len, const uint8_t *mi, int mi_len);
 const char *gsm48_mi_type_name(uint8_t mi);
 const char *osmo_mi_name(const uint8_t *mi, uint8_t mi_len);
 char *osmo_mi_name_buf(char *buf, size_t buf_len, const uint8_t *mi, uint8_t mi_len);