Fix type of dummy_irq()

src/core/nic.c

 	return 1;
 }
 
-int dummy_irq ( struct nic *nic __unused ) {
+int dummy_irq ( struct nic *nic __unused, irq_action_t irq_action __unused ) {
 	return 1;
 }
 

src/include/nic.h

 struct dev;
 extern struct nic * nic_device ( struct dev * dev );
 extern int dummy_connect ( struct nic *nic );
-extern int dummy_irq ( struct nic *nic );
+extern void dummy_irq ( struct nic *nic, irq_action_t irq_action );
 
 /*
  * Functions that implicitly operate on the current boot device