dmaengine: imx-sdma: use GFP_NOWAIT for dma descriptor allocations

DMA buffer descriptors aren't allocated from atomic context, so they
can use the less heavyweigth GFP_NOWAIT.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/imx-sdma.c

@@ -1214,7 +1214,7 @@ static int sdma_alloc_bd(struct sdma_desc *desc)
 	int ret = 0;
 
 	desc->bd = dma_zalloc_coherent(NULL, bd_size, &desc->bd_phys,
-					GFP_ATOMIC);
+					GFP_NOWAIT);
 	if (!desc->bd) {
 		ret = -ENOMEM;
 		goto out;