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 <gustavo.pimentel@synopsys.com>
Link: https://lore.kernel.org/r/4aa850c035cf7ee488f1d3fb6dee0e37be0dce0a.1613674948.git.gustavo.pimentel@synopsys.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

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

@@ -986,22 +986,21 @@ int dw_edma_remove(struct dw_edma_chip *chip)
 	/* Power management */
 	pm_runtime_disable(dev);
 
+	/* 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) {
-		list_del(&chan->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) {
-		list_del(&chan->vc.chan.device_node);
 		tasklet_kill(&chan->vc.task);
+		list_del(&chan->vc.chan.device_node);
 	}
 
-	/* Deregister eDMA device */
-	dma_async_device_unregister(&dw->wr_edma);
-	dma_async_device_unregister(&dw->rd_edma);
-
 	/* Turn debugfs off */
 	dw_edma_v0_core_debugfs_off(chip);