fs: Turn block_invalidatepage into block_invalidate_folio

Remove special-casing of a NULL invalidatepage, since there is no
more block_invalidatepage.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs
Tested-by: David Howells <dhowells@redhat.com> # afs
diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c
index ac628de..2d00578 100644
--- a/fs/ufs/inode.c
+++ b/fs/ufs/inode.c
@@ -527,6 +527,7 @@ static sector_t ufs_bmap(struct address_space *mapping, sector_t block)
 
 const struct address_space_operations ufs_aops = {
 	.set_page_dirty = __set_page_dirty_buffers,
+	.invalidate_folio = block_invalidate_folio,
 	.readpage = ufs_readpage,
 	.writepage = ufs_writepage,
 	.write_begin = ufs_write_begin,