driver core: fix some kernel-doc warnings in dma*.c

Fix kernel-doc warnings in drivers/base/dma*.c:

Warning(drivers/base/dma-buf.c:498): No description found for parameter 'vaddr'
Warning(drivers/base/dma-coherent.c:199): No description found for parameter 'ret'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/dma-buf.c

@@ -493,6 +493,7 @@ EXPORT_SYMBOL_GPL(dma_buf_vmap);
 /**
  * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
  * @dmabuf:	[in]	buffer to vunmap
+ * @vaddr:	[in]	vmap to vunmap
  */
 void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 {

drivers/base/dma-coherent.c

@@ -186,6 +186,7 @@ EXPORT_SYMBOL(dma_release_from_coherent);
  * @vma:	vm_area for the userspace memory
  * @vaddr:	cpu address returned by dma_alloc_from_coherent
  * @size:	size of the memory buffer allocated by dma_alloc_from_coherent
+ * @ret:	result from remap_pfn_range()
  *
  * This checks whether the memory was allocated from the per-device
  * coherent memory pool and if so, maps that memory to the provided vma.