fs/inode: Make relatime_need_update return bool

relatime_need_update should return bool to consistent with the function
__atime_needs_update that is caller

Signed-off-by: Hao Ge <gehao@kylinos.cn>
Link: https://lore.kernel.org/r/20231205064545.332322-1-gehao@kylinos.cn


Signed-off-by: Christian Brauner <brauner@kernel.org>