[hermon] Indicate that device does not support interrupts

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/infiniband/hermon.c

 	ib_poll_eq ( ibdev );
 }
 
-/**
- * Enable/disable interrupts on Hermon Ethernet device
- *
- * @v netdev		Network device
- * @v enable		Interrupts should be enabled
- */
-static void hermon_eth_irq ( struct net_device *netdev __unused,
-			     int enable __unused ) {
-	/* No implementation */
-}
-
 /**
  * Open Hermon Ethernet device
  *
 	.close		= hermon_eth_close,
 	.transmit	= hermon_eth_transmit,
 	.poll		= hermon_eth_poll,
-	.irq		= hermon_eth_irq,
 };
 
 /**