xarray.h: fix kernel-doc warning

Fix (Sphinx) kernel-doc warning in <linux/xarray.h>:

  include/linux/xarray.h:232: WARNING: Unexpected indentation.

Link: http://lkml.kernel.org/r/89ba2134-ce23-7c10-5ee1-ef83b35aa984@infradead.org
Fixes: a3e4d3f9 ("XArray: Redesign xa_alloc API")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/xarray.h

@@ -230,8 +230,8 @@ static inline int xa_err(void *entry)
  * This structure is used either directly or via the XA_LIMIT() macro
  * to communicate the range of IDs that are valid for allocation.
  * Two common ranges are predefined for you:
- *  * xa_limit_32b	- [0 - UINT_MAX]
- *  * xa_limit_31b	- [0 - INT_MAX]
+ * * xa_limit_32b	- [0 - UINT_MAX]
+ * * xa_limit_31b	- [0 - INT_MAX]
  */
 struct xa_limit {
 	u32 max;