gprs_ns2: Introduce gprs_ns2_create_nse2() for SGSN side SNS

gprs_ns2_create_nse() doesn't allow the caller to specify if the
BSS or the SGSN role of IP-SNS shall be implemented.  Add
gprs_ns2_create_nse2() to fix that.

Change-Id: I6db8c36f7c69b592d7d0fbcf323804f7e9912be2
Related: OS#3373
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index 588fabf..fc8ab45 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -139,6 +139,7 @@
 gprs_ns2_bind_by_name;
 gprs_ns2_cause_strs;
 gprs_ns2_create_nse;
+gprs_ns2_create_nse2;
 gprs_ns2_find_vc_by_sockaddr;
 gprs_ns2_free;
 gprs_ns2_free_bind;