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/media/dvb/bt8xx/bt878.c b/drivers/media/dvb/bt8xx/bt878.c
index eca602d..85e36a1d 100644
--- a/drivers/media/dvb/bt8xx/bt878.c
+++ b/drivers/media/dvb/bt8xx/bt878.c
@@ -280,7 +280,7 @@
 		if (!(astat = (stat & mask)))
 			return IRQ_NONE;	/* this interrupt is not for me */
 /*		dprintk("bt878(%d) debug: irq count %d, stat 0x%8.8x, mask 0x%8.8x\n",bt->nr,count,stat,mask); */
-		btwrite(astat, BT878_AINT_STAT);	/* try to clear interupt condition */
+		btwrite(astat, BT878_AINT_STAT);	/* try to clear interrupt condition */
 
 
 		if (astat & (BT878_ASCERR | BT878_AOCERR)) {