Staging: ipack/bridges/tpci200: Clean up interrupt handling.

Previously the return value from tpci200_interrupt was not quite correct
if a slot had caused an interrupt but no handler was instellalled:
IRQ_NONE was returned.  However in this case we react to the interrupt
by disabling the IPack device interrupt.

Basically there are two cases the code now distinguishes:
 - The tpci200 has raised an interrupt.  We handle it and return
   IRQ_HANDLED.
 - Our device did not raise an interrupt. We return IRQ_NONE.
Signed-off-by: Jens Taprogge <jens.taprogge@taprogge.org>
Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/ipack/bridges/tpci200.c

@@ -116,7 +116,6 @@ static irqreturn_t tpci200_interrupt(int irq, void *dev_id)
 	struct tpci200_board *tpci200 = (struct tpci200_board *) dev_id;
 	int i;
 	unsigned short status_reg;
-	irqreturn_t ret = IRQ_NONE;
 	struct slot_irq *slot_irq;
 
 	/* Read status register */
@@ -130,7 +129,7 @@ static irqreturn_t tpci200_interrupt(int irq, void *dev_id)
 				continue;
 			slot_irq = rcu_dereference(tpci200->slots[i].irq);
 			if (slot_irq) {
-				ret = tpci200_slot_irq(slot_irq);
+				tpci200_slot_irq(slot_irq);
 			} else {
 				dev_info(&tpci200->info->pdev->dev,
 					 "No registered ISR for slot [%d:%d]!. IRQ will be disabled.\n",
@@ -141,9 +140,11 @@ static irqreturn_t tpci200_interrupt(int irq, void *dev_id)
 			}
 		}
 		rcu_read_unlock();
-	}
 
-	return ret;
+		return IRQ_HANDLED;
+	} else {
+		return IRQ_NONE;
+	}
 }
 
 static int tpci200_register(struct tpci200_board *tpci200)