ecryptfs: Convert ecryptfs_encrypt_page() to take a folio

All three callers have a folio, so pass it in and use it throughout.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20241025190822.1319162-8-willy@infradead.org


Signed-off-by: Christian Brauner <brauner@kernel.org>