[netdrvr] irq handler minor cleanups in several drivers

* use irq_handler_t where appropriate

* no need to use 'irq' function arg, its already stored in a data struct

* rename irq handler 'irq' argument to 'dummy', where the function
  has been analyzed and proven not to use its first argument.

* remove always-false "dev_id == NULL" test from irq handlers

* remove pointless casts from void*

* declance: irq argument is not const

* add KERN_xxx printk prefix

* fix minor whitespace weirdness

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index a4265bc..88341bf 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -734,7 +734,7 @@
 {
 	struct net_device *netdev = adapter->netdev;
 	int flags, err;
-	irqreturn_t(*handler) (int, void *) = &ixgbe_intr;
+	irq_handler_t handler = ixgbe_intr;
 
 	flags = IRQF_SHARED;