isisd: fix network-type configuration

Reported-by: Martin Winter <mwinter@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/isisd/isis_vty.c b/isisd/isis_vty.c
index 3ce06b8..f9b96a4 100644
--- a/isisd/isis_vty.c
+++ b/isisd/isis_vty.c
@@ -255,7 +255,7 @@
   if (!circuit)
     return CMD_ERR_NO_MATCH;
 
-  if (!isis_circuit_circ_type_set(circuit, CIRCUIT_T_P2P))
+  if (isis_circuit_circ_type_set(circuit, CIRCUIT_T_P2P))
     {
       vty_out (vty, "isis network point-to-point "
                "is valid only on broadcast interfaces%s",
@@ -278,7 +278,7 @@
   if (!circuit)
     return CMD_ERR_NO_MATCH;
 
-  if (!isis_circuit_circ_type_set(circuit, CIRCUIT_T_BROADCAST))
+  if (isis_circuit_circ_type_set(circuit, CIRCUIT_T_BROADCAST))
     {
       vty_out (vty, "isis network point-to-point "
                "is valid only on broadcast interfaces%s",