dmaengine: s3c24xx: kill the tasklets upon exit

drivers should ensure that tasklets are killed, so that they can't be
executed after driver remove is executed, so ensure they are killed.

This driver used vchan tasklets, so those need to be killed.

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

drivers/dma/s3c24xx-dma.c

@@ -1136,8 +1136,10 @@ static void s3c24xx_dma_free_virtual_channels(struct dma_device *dmadev)
 	struct s3c24xx_dma_chan *next;
 
 	list_for_each_entry_safe(chan,
-				 next, &dmadev->channels, vc.chan.device_node)
+				 next, &dmadev->channels, vc.chan.device_node) {
 		list_del(&chan->vc.chan.device_node);
+		tasklet_kill(&chan->vc.task);
+	}
 }
 
 /* s3c2410, s3c2440 and s3c2442 have a 0x40 stride without separate clocks */