[SCSI] NCR5380: Fix bugs and canonicalize irq handler usage

* Always pass the same value to free_irq() that we pass to
  request_irq().  This fixes several bugs.

* Always call NCR5380_intr() with 'irq' and 'dev_id' arguments.

  Note, scsi_falcon_intr() is the only case now where dev_id is not the
  scsi_host.

* Always pass Scsi_Host to request_irq().  For most cases, the drivers
  already did so, and I merely neated the source code line.  In other
  cases, either NULL or a non-sensical value was passed, verified to be
  unused, then changed to be Scsi_Host in anticipation of the future.

In addition to the bugs fixes, this change makes the interface usage
consistent, which in turn enables the possibility of directly
referencing Scsi_Host from all NCR5380_intr() invocations.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/pas16.c b/drivers/scsi/pas16.c
index ee59656..f2018b4 100644
--- a/drivers/scsi/pas16.c
+++ b/drivers/scsi/pas16.c
@@ -453,7 +453,8 @@
 	    instance->irq = NCR5380_probe_irq(instance, PAS16_IRQS);
 
 	if (instance->irq != SCSI_IRQ_NONE) 
-	    if (request_irq(instance->irq, pas16_intr, IRQF_DISABLED, "pas16", instance)) {
+	    if (request_irq(instance->irq, pas16_intr, IRQF_DISABLED,
+			    "pas16", instance)) {
 		printk("scsi%d : IRQ%d not free, interrupts disabled\n", 
 		    instance->host_no, instance->irq);
 		instance->irq = SCSI_IRQ_NONE;
@@ -604,7 +605,7 @@
 static int pas16_release(struct Scsi_Host *shost)
 {
 	if (shost->irq)
-		free_irq(shost->irq, NULL);
+		free_irq(shost->irq, shost);
 	NCR5380_exit(shost);
 	if (shost->dma_channel != 0xff)
 		free_dma(shost->dma_channel);