nilfs2: switch to kmap_local for directory handling

nilfs2: switch to kmap_local for directory handling

Match ext2 by using kmap_local() instead of kmap().  This is more
efficient.  Also use unmap_and_put_page() instead of duplicating it as a
nilfs function.

[konishi.ryusuke: followed the change of page release helper call sites]
Link: https://lkml.kernel.org/r/20231127143036.2425-9-konishi.ryusuke@gmail.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>