ASoC: atmel: patch for the unnecessary variable removal

The variable 'periods' of structure 'atmel_runtime_data'
seems no use in whole atmel alsa driver,so I make a patch
to remove the unnecessary variable.

Signed-off-by: Wan ZongShun <mcuos.com@gmail.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/atmel/atmel-pcm.c

@@ -77,7 +77,6 @@ struct atmel_runtime_data {
 	size_t period_size;
 
 	dma_addr_t period_ptr;		/* physical address of next period */
-	int periods;			/* period index of period_ptr */
 
 	/* PDC register save */
 	u32 pdc_xpr_save;