vty/telnet_interface: Add telnet_exit function

This frees socket and pending connections

Written-by: Andreas Eversberg <jolly@eversberg.eu>
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/vty/telnet_interface.h b/include/osmocom/vty/telnet_interface.h
index 9a7c9e5..2de4f19 100644
--- a/include/osmocom/vty/telnet_interface.h
+++ b/include/osmocom/vty/telnet_interface.h
@@ -48,6 +48,8 @@
 
 int telnet_init(void *tall_ctx, void *priv, int port);
 
+void telnet_exit(void);
+
 /*! }@ */
 
 #endif /* TELNET_INTERFACE_H */