UBI: align comment for readability

The kerneldoc for @vid_hdr_aloffset continues onto a second line, but
this is not obvious, because the second line isn't indented, and it
begins with '@'.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/ubi.h

@@ -479,7 +479,7 @@ struct ubi_debug_info {
  * @vid_hdr_offset: starting offset of the volume identifier header (might be
  *                  unaligned)
  * @vid_hdr_aloffset: starting offset of the VID header aligned to
- * @hdrs_min_io_size
+ *                    @hdrs_min_io_size
  * @vid_hdr_shift: contains @vid_hdr_offset - @vid_hdr_aloffset
  * @bad_allowed: whether the MTD device admits of bad physical eraseblocks or
  *               not