dmaengine: virt-dma: convert tasklets to use new tasklet_setup() API

In preparation for unconditionally passing the
struct tasklet_struct pointer to all tasklet
callbacks, switch to using the new tasklet_setup()
and from_tasklet() to pass the tasklet pointer explicitly.

Signed-off-by: Romain Perier <[e-mail]>
Signed-off-by: Allen Pais <[e-mail]>
Reviewed-by: Peter Ujfalusi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/virt-dma.c

···
  * This tasklet handles the completion of a DMA descriptor by
  * calling its callback and freeing it.
  */
-static void vchan_complete(unsigned long arg)
+static void vchan_complete(struct tasklet_struct *t)
 {
-	struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
+	struct virt_dma_chan *vc = from_tasklet(vc, t, task);
 	struct virt_dma_desc *vd, *_vd;
 	struct dmaengine_desc_callback cb;
 	LIST_HEAD(head);
···
 	INIT_LIST_HEAD(&vc->desc_completed);
 	INIT_LIST_HEAD(&vc->desc_terminated);
 
-	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
+	tasklet_setup(&vc->task, vchan_complete);
 
 	vc->chan.device = dmadev;
 	list_add_tail(&vc->chan.device_node, &dmadev->channels);