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/drivers/net/irda/donauboe.c b/drivers/net/irda/donauboe.c
index a82d8f9..1257e1a 100644
--- a/drivers/net/irda/donauboe.c
+++ b/drivers/net/irda/donauboe.c
@@ -595,7 +595,7 @@
   OUTB ((physaddr >> 18) & 0xff, OBOE_RING_BASE1);
   OUTB ((physaddr >> 26) & 0x3f, OBOE_RING_BASE2);
 
-  /*Enable DMA controler in byte mode and RX */
+  /*Enable DMA controller in byte mode and RX */
   OUTB (CONFIG0H_DMA_ON, OBOE_CONFIG0H);
 
   /* Start up the clocks */