dmaengine: xilinx_dma: Alloc tx descriptors GFP_NOWAIT

Use GFP_NOWAIT allocation in xilinx_dma_alloc_tx_descriptor().

This is necessary for compatibility with ALSA, which calls
dmaengine_prep_dma_cyclic() from an atomic context.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210129170800.31857-1-rf@opensource.cirrus.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/xilinx/xilinx_dma.c

@@ -800,7 +800,7 @@ xilinx_dma_alloc_tx_descriptor(struct xilinx_dma_chan *chan)
 {
 	struct xilinx_dma_tx_descriptor *desc;
 
-	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+	desc = kzalloc(sizeof(*desc), GFP_NOWAIT);
 	if (!desc)
 		return NULL;