buffer: Convert block_write_end() to take a folio

All callers now have a folio, so pass it in instead of converting
from a folio to a page and back to a folio again.  Saves a call
to compound_head().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block/fops.c

@@ -462,7 +462,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
 {
 	struct folio *folio = page_folio(page);
 	int ret;
-	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+	ret = block_write_end(file, mapping, pos, len, copied, folio, fsdata);
 
 	folio_unlock(folio);
 	folio_put(folio);