dmaengine: zynqmp_dma: Fix kernel doc-format

This patch fixes the below kernel doc warnings
drivers/dma/xilinx/zynqmp_dma.c:552: info: Scanning doc for
zynqmp_dma_device_config
drivers/dma/xilinx/zynqmp_dma.c:558: warning: No description found for
return value of 'zynqmp_dma_device_config'
drivers/dma/xilinx/zynqmp_dma.c:649: info: Scanning doc for
zynqmp_dma_free_descriptors
drivers/dma/xilinx/zynqmp_dma.c:653: warning: No description found for
parameter 'chan'
drivers/dma/xilinx/zynqmp_dma.c:653: warning: Excess function parameter
'dchan' description in 'zynqmp_dma_free_descriptors'

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

drivers/dma/xilinx/zynqmp_dma.c

@@ -552,6 +552,8 @@ static void zynqmp_dma_config(struct zynqmp_dma_chan *chan)
  * zynqmp_dma_device_config - Zynqmp dma device configuration
  * @dchan: DMA channel
  * @config: DMA device config
+ *
+ * Return: 0 always
  */
 static int zynqmp_dma_device_config(struct dma_chan *dchan,
 				    struct dma_slave_config *config)
@@ -647,7 +649,7 @@ static void zynqmp_dma_issue_pending(struct dma_chan *dchan)
 
 /**
  * zynqmp_dma_free_descriptors - Free channel descriptors
- * @dchan: DMA channel pointer
+ * @chan: ZynqMP DMA channel pointer
  */
 static void zynqmp_dma_free_descriptors(struct zynqmp_dma_chan *chan)
 {