fs: convert clean_buffers() to take a folio

The only caller already has a folio, so pass it in and use it throughout. 
Saves two calls to compound_head().

Link: https://lkml.kernel.org/r/20231215200245.748418-3-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>