ASoC/mpc5200: fix enable/disable of AC97 slots

The MPC5200 AC97 driver is disabling the slots when a stop
trigger is received, but not reenabling them if the stream
is started again without processing the hw_params again.

This patch fixes the problem by caching the slot enable bit
settings calculated at hw_params time so that they can be
reapplied every time the start trigger is received.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/fsl/mpc5200_dma.h b/sound/soc/fsl/mpc5200_dma.h
index 956d6a5..22208b3 100644
--- a/sound/soc/fsl/mpc5200_dma.h
+++ b/sound/soc/fsl/mpc5200_dma.h
@@ -16,6 +16,7 @@
  * @period_end:		physical address of end of DMA region
  * @period_next_pt:	physical address of next DMA buffer to enqueue
  * @period_bytes:	size of DMA period in bytes
+ * @ac97_slot_bits:	Enable bits for turning on the correct AC97 slot
  */
 struct psc_dma_stream {
 	struct snd_pcm_runtime *runtime;
@@ -28,6 +29,9 @@
 	int period_current;
 	int period_bytes;
 	int period_count;
+
+	/* AC97 state */
+	u32 ac97_slot_bits;
 };
 
 /**