dmaengine: dw-edma: Fix crash on loading/unloading driver

When the driver is compiled as a module and loaded if we try to unload
it, the Kernel shows a crash log. This Kernel crash is due to the
dma_async_device_unregister() call done after deleting the channels,
this patch fixes this issue.

Signed-off-by: Gustavo Pimentel <[e-mail]>
Link: https://lore.kernel.org/r/4aa850c0[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/dw-edma/dw-edma-core.c

···
 	/* Power management */
 	pm_runtime_disable(dev);
 
-	list_for_each_entry_safe(chan, _chan, &dw->wr_edma.channels,
-				 vc.chan.device_node) {
-		list_del(&chan->vc.chan.device_node);
-		tasklet_kill(&chan->vc.task);
-	}
-
-	list_for_each_entry_safe(chan, _chan, &dw->rd_edma.channels,
-				 vc.chan.device_node) {
-		list_del(&chan->vc.chan.device_node);
-		tasklet_kill(&chan->vc.task);
-	}
-
 	/* Deregister eDMA device */
 	dma_async_device_unregister(&dw->wr_edma);
+	list_for_each_entry_safe(chan, _chan, &dw->wr_edma.channels,
+				 vc.chan.device_node) {
+		tasklet_kill(&chan->vc.task);
+		list_del(&chan->vc.chan.device_node);
+	}
+
 	dma_async_device_unregister(&dw->rd_edma);
+	list_for_each_entry_safe(chan, _chan, &dw->rd_edma.channels,
+				 vc.chan.device_node) {
+		tasklet_kill(&chan->vc.task);
+		list_del(&chan->vc.chan.device_node);
+	}
 
 	/* Turn debugfs off */
 	dw_edma_v0_core_debugfs_off(chip);