ext4: Convert ext4_readpage_inline() to take a folio

Use the folio API in this function, saves 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/20230324180129.1220691-10-willy@infradead.org


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