Fix misspellings of "system", "controller", "interrupt" and "necessary".

Fix the various misspellings of "system", controller", "interrupt" and
"[un]necessary".

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
diff --git a/net/irda/discovery.c b/net/irda/discovery.c
index af0cea7..80c33f4 100644
--- a/net/irda/discovery.c
+++ b/net/irda/discovery.c
@@ -202,7 +202,7 @@
 	/* Drop the spinlock before calling the higher layers, as
 	 * we can't guarantee they won't call us back and create a
 	 * deadlock. We will work on our own private data, so we
-	 * don't care to be interupted. - Jean II */
+	 * don't care to be interrupted. - Jean II */
 	spin_unlock_irqrestore(&log->hb_spinlock, flags);
 
 	if(buffer == NULL)