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>

drivers/serial/mpc52xx_uart.c

@@ -512,19 +512,11 @@ mpc52xx_uart_int_tx_chars(struct uart_port *port)
 static irqreturn_t 
 mpc52xx_uart_int(int irq, void *dev_id)
 {
-	struct uart_port *port = (struct uart_port *) dev_id;
+	struct uart_port *port = dev_id;
 	unsigned long pass = ISR_PASS_LIMIT;
 	unsigned int keepgoing;
 	unsigned short status;
 	
-	if ( irq != port->irq ) {
-		printk( KERN_WARNING
-		        "mpc52xx_uart_int : " \
-		        "Received wrong int %d. Waiting for %d\n",
-		       irq, port->irq);
-		return IRQ_NONE;
-	}
-	
 	spin_lock(&port->lock);
 	
 	/* While we have stuff to do, we continue */