dmaengine: xilinx_dma: Fix warning variable prev set but not used

This patch fixes the below sparse warning in the driver
drivers/dma/xilinx/xilinx_dma.c: In function ‘xilinx_vdma_dma_prep_interleaved’:
drivers/dma/xilinx/xilinx_dma.c:1614:43: warning: variable ‘prev’ set but not used [-Wunused-but-set-variable]
  struct xilinx_vdma_tx_segment *segment, *prev = NULL;

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/xilinx/xilinx_dma.c

@@ -1611,7 +1611,7 @@ xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
 {
 	struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
 	struct xilinx_dma_tx_descriptor *desc;
-	struct xilinx_vdma_tx_segment *segment, *prev = NULL;
+	struct xilinx_vdma_tx_segment *segment;
 	struct xilinx_vdma_desc_hw *hw;
 
 	if (!is_slave_direction(xt->dir))
@@ -1665,8 +1665,6 @@ xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
 	/* Insert the segment into the descriptor segments list. */
 	list_add_tail(&segment->node, &desc->segments);
 
-	prev = segment;
-
 	/* Link the last hardware descriptor with the first. */
 	segment = list_first_entry(&desc->segments,
 				   struct xilinx_vdma_tx_segment, node);