fs: Pass a folio to page_put_link()

All callers now have a folio.  Pass it to page_put_link(), saving a
hidden call to compound_head().  Also add kernel-doc for page_get_link()
and page_put_link().

Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Link: https://lore.kernel.org/20250514171316.3002934-4-willy@infradead.org


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