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/sound/drivers/opl3/opl3_midi.c b/sound/drivers/opl3/opl3_midi.c
index 1b6f227..3557b6e 100644
--- a/sound/drivers/opl3/opl3_midi.c
+++ b/sound/drivers/opl3/opl3_midi.c
@@ -808,7 +808,7 @@
 }
 
 /*
- * Deal with a controler type event.  This includes all types of
+ * Deal with a controller type event.  This includes all types of
  * control events, not just the midi controllers
  */
 void snd_opl3_control(void *p, int type, struct snd_midi_channel *chan)