Add kernel-doc style comments for swiotlb_del_transient function.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9513
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
---
 kernel/dma/swiotlb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index b4d8167b2f8d..df68d29740a0 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -1500,6 +1500,7 @@ static void swiotlb_release_slots(struct device *dev, phys_addr_t tlb_addr,
  * swiotlb_del_transient() - delete a transient memory pool
  * @dev:	Device which mapped the buffer.
  * @tlb_addr:	Physical address within a bounce buffer.
+ * @pool:       Pointer to the transient memory pool to be checked and deleted.
  *
  * Check whether the address belongs to a transient SWIOTLB memory pool.
  * If yes, then delete the pool.
-- 
2.20.1.7.g153144c

The kernel-doc comment is not missing, the desctiption of the new
paramter is.  I've updated the commit log and dropped the pointless
closes.

Thanks for the patch!