gprs_ns2: add gprs_ns2_ip_vc_equal()

Compare the NS-VC with the given parameter

Change-Id: I3a0cd305fd73b3cb9ec70246ec15ac70b83e57f2
diff --git a/include/osmocom/gprs/gprs_ns2.h b/include/osmocom/gprs/gprs_ns2.h
index 6f33f79..497265e 100644
--- a/include/osmocom/gprs/gprs_ns2.h
+++ b/include/osmocom/gprs/gprs_ns2.h
@@ -147,6 +147,10 @@
 
 const struct osmo_sockaddr *gprs_ns2_ip_vc_remote(const struct gprs_ns2_vc *nsvc);
 const struct osmo_sockaddr *gprs_ns2_ip_vc_local(const struct gprs_ns2_vc *nsvc);
+bool gprs_ns2_ip_vc_equal(const struct gprs_ns2_vc *nsvc,
+			  const struct osmo_sockaddr *local,
+			  const struct osmo_sockaddr *remote,
+			  uint16_t nsvci);
 const struct osmo_sockaddr *gprs_ns2_ip_bind_sockaddr(struct gprs_ns2_vc_bind *bind);
 int gprs_ns2_is_ip_bind(struct gprs_ns2_vc_bind *bind);
 int gprs_ns2_ip_bind_set_dscp(struct gprs_ns2_vc_bind *bind, int dscp);