isdn: Fix typo in drivers/isdn

Correct spelling typo in printk within drivers/isdn

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/pcbit/layer2.c b/drivers/isdn/pcbit/layer2.c
index a18e639..42ecfef 100644
--- a/drivers/isdn/pcbit/layer2.c
+++ b/drivers/isdn/pcbit/layer2.c
@@ -508,7 +508,7 @@
 		return IRQ_NONE;
 	}
 	if (dev->interrupt) {
-		printk(KERN_DEBUG "pcbit: reentering interrupt hander\n");
+		printk(KERN_DEBUG "pcbit: reentering interrupt handler\n");
 		return IRQ_HANDLED;
 	}
 	dev->interrupt = 1;