document xilinx_dma_device_config() return value. Fixes below
kernel-doc warning.

xilinx_dma.c:1665: warning: No description found for return value
of 'xilinx_dma_device_config'

Fixes: 4153a7f6440f ("dmaengine: xilinx: Add empty device_config function")
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
---
 drivers/dma/xilinx/xilinx_dma.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 3b8cfeccf2da..a8d23cdf883e 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -1659,6 +1659,8 @@ static void xilinx_dma_issue_pending(struct dma_chan *dchan)
  * xilinx_dma_device_config - Configure the DMA channel
  * @dchan: DMA channel
  * @config: channel configuration
+ *
+ * Return: 0 always.
  */
 static int xilinx_dma_device_config(struct dma_chan *dchan,
 				    struct dma_slave_config *config)
-- 
2.25.1