Various drivers' irq handlers: kill dead code, needless casts

- Eliminate casts to/from void*

- Eliminate checks for conditions that never occur.  These typically
  fall into two classes:

	1) Checking for 'dev_id == NULL', then it is never called with
	NULL as an argument.

	2) Checking for invalid irq number, when the only caller (the
	system) guarantees the irq handler is called with the proper
	'irq' number argument.

Signed-off-by: Jeff Garzik <jeff@garzik.org>

sound/pci/korg1212/korg1212.c

@@ -1124,9 +1124,6 @@ static irqreturn_t snd_korg1212_interrupt(int irq, void *dev_id)
         u32 doorbellValue;
         struct snd_korg1212 *korg1212 = dev_id;
 
-	if(irq != korg1212->irq)
-		return IRQ_NONE;
-
         doorbellValue = readl(korg1212->inDoorbellPtr);
 
         if (!doorbellValue)
@@ -1140,7 +1137,6 @@ static irqreturn_t snd_korg1212_interrupt(int irq, void *dev_id)
 
 	korg1212->inIRQ++;
 
-
         switch (doorbellValue) {
                 case K1212_DB_DSPDownloadDone:
                         K1212_DEBUG_PRINTK("K1212_DEBUG: IRQ DNLD count - %ld, %x, [%s].\n",