dmaengine: at_hdmac: add missing kfree() call in at_dma_xlate()

If memory allocation for 'atslave' succeed, at_dma_xlate() doesn't have a
corresponding kfree() in exception handling. Thus add kfree() for this
function implementation.

Fixes: bbe89c8e3d ("at_hdmac: move to generic DMA binding")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20200817115728.1706719-4-yukuai3@huawei.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/at_hdmac.c

@@ -1691,6 +1691,7 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
 	chan = dma_request_channel(mask, at_dma_filter, atslave);
 	if (!chan) {
 		put_device(&dmac_pdev->dev);
+		kfree(atslave);
 		return NULL;
 	}