Add strings for GPRS ciphers

Change-Id: I050bda5fb50aad42fe2d72de39f8256b4fb12fb2
Related: OS#1582
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index ea2101c..ebeabcd 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -39,6 +39,7 @@
 gprs_cipher_load;
 gprs_cipher_register;
 gprs_cipher_run;
+gprs_cipher_names;
 gprs_cipher_supported;
 gprs_cipher_key_length;
 gprs_tlli_type;