dma-mapping: fix the kerneldoc for dma_map_sgtable()

htmldocs began producing the following warnings:

  kernel/dma/mapping.c:256: WARNING: Definition list ends without a
             blank line; unexpected unindent.
  kernel/dma/mapping.c:257: WARNING: Bullet list ends without a blank
             line; unexpected unindent.

Reformatting the list without hyphens fixes the warnings and produces
both a readable text and HTML output.

Fixes: fffe3cc8 ("dma-mapping: allow map_sg() ops to return negative error code")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

kernel/dma/mapping.c

@@ -249,12 +249,12 @@ EXPORT_SYMBOL(dma_map_sg_attrs);
  * Returns 0 on success or a negative error code on error. The following
  * error codes are supported with the given meaning:
  *
- *   -EINVAL - An invalid argument, unaligned access or other error
- *	       in usage. Will not succeed if retried.
- *   -ENOMEM - Insufficient resources (like memory or IOVA space) to
- *	       complete the mapping. Should succeed if retried later.
- *   -EIO    - Legacy error code with an unknown meaning. eg. this is
- *	       returned if a lower level call returned DMA_MAPPING_ERROR.
+ *   -EINVAL	An invalid argument, unaligned access or other error
+ *		in usage. Will not succeed if retried.
+ *   -ENOMEM	Insufficient resources (like memory or IOVA space) to
+ *		complete the mapping. Should succeed if retried later.
+ *   -EIO	Legacy error code with an unknown meaning. eg. this is
+ *		returned if a lower level call returned DMA_MAPPING_ERROR.
  */
 int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
 		    enum dma_data_direction dir, unsigned long attrs)