gprs_ns2: add gprs_ns2_free_binds() to free all binds

Allow users to clean up all binds (e.g. the PCU).

Change-Id: Ic8f6f8aca10da23a18fab8870be7806065a34b47
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index 3d1d5d6..d23d263 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -79,6 +79,7 @@
 gprs_ns2_find_vc_by_sockaddr;
 gprs_ns2_free;
 gprs_ns2_free_bind;
+gprs_ns2_free_binds;
 gprs_ns2_free_nse;
 gprs_ns2_free_nsvc;
 gprs_ns2_frgre_bind;