udf: Convert udf_symlink_filler() to use a folio

Remove the conversion to struct page and use folio APIs throughout.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240417150416.752929-2-willy@infradead.org>