fsldma: major cleanups and fixes

Fix locking. Use two queues in the driver, one for pending transacions, and
one for transactions which are actually running on the hardware. Call
dma_run_dependencies() on descriptor cleanup so that the async_tx API works
correctly.

There are a number of places throughout the code where lists of descriptors
are freed in a loop. Create functions to handle this, and use them instead
of open-coding the loop each time.
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/fsldma.h

@@ -131,7 +131,8 @@ struct fsldma_chan {
 	struct fsldma_chan_regs __iomem *regs;
 	dma_cookie_t completed_cookie;	/* The maximum cookie completed */
 	spinlock_t desc_lock;		/* Descriptor operation lock */
-	struct list_head ld_queue;	/* Link descriptors queue */
+	struct list_head ld_pending;	/* Link descriptors queue */
+	struct list_head ld_running;	/* Link descriptors queue */
 	struct dma_chan common;		/* DMA common channel */
 	struct dma_pool *desc_pool;	/* Descriptors pool */
 	struct device *dev;		/* Channel device */