ASoC: atmel_pcm: Remove non-existant header

<mach/hardware.h> doesn't exist on AVR32 and therefore this driver won't
build on that arch.  AFAICT this driver doesn't actually use the content
of that header so easiest just to remove it.
Signed-off-by: Ben Nizette <bn@niasdigital.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/atmel/atmel-pcm.c

@@ -44,8 +44,6 @@
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
 
-#include <mach/hardware.h>
-
 #include "atmel-pcm.h"