isisd: API: LSP-MTU & area level

Yet more CLI functions in isis_vty.c using more nice setters.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/isisd/isisd.h b/isisd/isisd.h
index 691d134..2ba44d8 100644
--- a/isisd/isisd.h
+++ b/isisd/isisd.h
@@ -146,6 +146,8 @@
 void isis_area_dynhostname_set(struct isis_area *area, bool dynhostname);
 void isis_area_metricstyle_set(struct isis_area *area, bool old_metric,
 			       bool new_metric);
+void isis_area_lsp_mtu_set(struct isis_area *area, unsigned int lsp_mtu);
+void isis_area_is_type_set(struct isis_area *area, int is_type);
 
 void isis_vty_init (void);