dmaengine: xilinx_dma: Remove set but unused ‘tail_desc’

We get a compiler warn about variable ‘tail_desc’ set but not used

drivers/dma/xilinx/xilinx_dma.c:1102:42: warning:
	variable ‘tail_desc’ set but not used [-Wunused-but-set-variable]
  struct xilinx_dma_tx_descriptor *desc, *tail_desc;

So remove it.
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/xilinx/xilinx_dma.c

@@ -1099,7 +1099,7 @@ static void xilinx_dma_start(struct xilinx_dma_chan *chan)
 static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 {
 	struct xilinx_vdma_config *config = &chan->config;
-	struct xilinx_dma_tx_descriptor *desc, *tail_desc;
+	struct xilinx_dma_tx_descriptor *desc;
 	u32 reg, j;
 	struct xilinx_vdma_tx_segment *segment, *last = NULL;
 	int i = 0;
@@ -1116,8 +1116,6 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
 
 	desc = list_first_entry(&chan->pending_list,
 				struct xilinx_dma_tx_descriptor, node);
-	tail_desc = list_last_entry(&chan->pending_list,
-				    struct xilinx_dma_tx_descriptor, node);
 
 	/* Configure the hardware using info in the config structure */
 	if (chan->has_vflip) {