maple_tree: change return type of mas_split_final_node as void.

mas_split_final_node() always returns true and its return value is never
checked.

Change return type to void.

Link: https://lkml.kernel.org/r/20231109160821.16248-2-ppbuk5246@gmail.com


Signed-off-by: Levi Yun <ppbuk5246@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>