dmaengine: omap-dma: Fix memory leak when terminating running transfer

In omap_dma_start_desc the vdesc->node is removed from the virt-dma
framework managed lists (to be precise from the desc_issued list).
If a terminate_all comes before the transfer finishes the omap_desc will
not be freed up because it is not in any of the lists and we stopped the
DMA channel so the transfer will not going to complete.
There is no special sequence for leaking memory when using cyclic (audio)
transfer: with every start and stop of a cyclic transfer the driver leaks
struct omap_desc worth of memory.

Free up the allocated memory directly in omap_dma_terminate_all() since the
framework will not going to do that for us.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
CC: <stable@vger.kernel.org>
CC: <linux-omap@vger.kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>