mm/memblock: fix comment for memblock_isolate_range()

The isolated range is [*@start_rgn, *@end_rgn - 1], while the comment says
"the end region inside the range" is *@end_rgn.

Let's correct it.

Signed-off-by: Wei Yang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mike Rapoport (IBM) <[e-mail]>

mm/memblock.c

···
  * Walk @type and ensure that regions don't cross the boundaries defined by
  * [@base, @base + @size).  Crossing regions are split at the boundaries,
  * which may create at most two more regions.  The index of the first
- * region inside the range is returned in *@start_rgn and end in *@end_rgn.
+ * region inside the range is returned in *@start_rgn and the index of the
+ * first region after the range is returned in *@end_rgn.
  *
  * Return:
  * 0 on success, -errno on failure.