ext4: Use a folio in ext4_journalled_write_end()

Convert the incoming page to a folio to remove a few calls to
compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230324180129.1220691-19-willy@infradead.org


Signed-off-by: Theodore Ts'o <tytso@mit.edu>