soc: ti: knav_dma: Fix a kernel function doc formatting issue

Fixes the following W=1 kernel build warning(s):

 drivers/soc/ti/knav_dma.c:507: warning: Function parameter or member 'channel' not described in 'knav_dma_close_channel'

Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Sandeep Nair <sandeep_n@ti.com>
Cc: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

drivers/soc/ti/knav_dma.c

@@ -500,7 +500,7 @@ EXPORT_SYMBOL_GPL(knav_dma_open_channel);
 /**
  * knav_dma_close_channel()	- Destroy a dma channel
  *
- * channel:	dma channel handle
+ * @channel:	dma channel handle
  *
  */
 void knav_dma_close_channel(void *channel)