isisd: fix is_type_set

Code's "is_type" is "circuit-type" in CLI, "circuit_type" is "network"
(type) in CLI, and the function to change is_type is
isis_event_circuit_type_change()... *headdesk*

Reported-by: Martin Winter <mwinter@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/isisd/isis_circuit.c b/isisd/isis_circuit.c
index bbe06b5..4750c5c 100644
--- a/isisd/isis_circuit.c
+++ b/isisd/isis_circuit.c
@@ -1284,10 +1284,10 @@
 }
 
 void
-isis_circuit_is_type_set (struct isis_circuit *circuit, int circ_type)
+isis_circuit_is_type_set (struct isis_circuit *circuit, int is_type)
 {
-  if (circuit->circ_type != circ_type)
-    isis_event_circuit_type_change (circuit, circ_type);
+  if (circuit->is_type != is_type)
+    isis_event_circuit_type_change (circuit, is_type);
 }
 
 int