gprs_ns2: add gprs_ns2_nse_foreach_nsvc()

Allow to loop over all NSVC within a NSE via a callback

Change-Id: I5a2bb95d05d06d909347e2fb084a446ead888cb3
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index e6557b7..eea1285 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -101,6 +101,7 @@
 gprs_ns2_ll_str_buf;
 gprs_ns2_ll_str_c;
 gprs_ns2_nse_by_nsei;
+gprs_ns2_nse_foreach_nsvc;
 gprs_ns2_nse_nsei;
 gprs_ns2_nse_sns_remote;
 gprs_ns2_nsvc_by_nsvci;