nilfs2: remove page_address() from nilfs_delete_entry

In preparation for removing kmap from directory handling, mask the
directory entry pointer to discover the start address of the page. 
Matches ext2.

Link: https://lkml.kernel.org/r/20231127143036.2425-6-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>