ns2: Fix assert when removing a bind listen

Change-Id: I3edd1e838f7516d9224045710047419039aa0ec0
Fixes: OS#4977
diff --git a/src/gb/gprs_ns2_vty.c b/src/gb/gprs_ns2_vty.c
index 1c40759..c2b9bd9 100644
--- a/src/gb/gprs_ns2_vty.c
+++ b/src/gb/gprs_ns2_vty.c
@@ -516,7 +516,7 @@
 	if (!bind)
 		return CMD_ERR_NOTHING_TODO;
 
-	OSMO_ASSERT(bind->ll != GPRS_NS2_LL_UDP);
+	OSMO_ASSERT(bind->ll == GPRS_NS2_LL_UDP);
 	bind->driver->free_bind(bind);
 	return CMD_SUCCESS;
 }