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/isa/es18xx.c b/sound/isa/es18xx.c
index 4a7367a..c1af28f 100644
--- a/sound/isa/es18xx.c
+++ b/sound/isa/es18xx.c
@@ -623,7 +623,7 @@
                          (snd_pcm_format_width(runtime->format) == 16 ? 0x04 : 0x00) |
                          (snd_pcm_format_unsigned(runtime->format) ? 0x00 : 0x20));
 
-        /* Set DMA controler */
+        /* Set DMA controller */
         snd_dma_program(chip->dma1, runtime->dma_addr, size, DMA_MODE_READ | DMA_AUTOINIT);
 
 	return 0;
@@ -689,7 +689,7 @@
                          (snd_pcm_format_width(runtime->format) == 16 ? 0x04 : 0x00) |
                          (snd_pcm_format_unsigned(runtime->format) ? 0x00 : 0x20));
 
-        /* Set DMA controler */
+        /* Set DMA controller */
         snd_dma_program(chip->dma1, runtime->dma_addr, size, DMA_MODE_WRITE | DMA_AUTOINIT);
 
 	return 0;