hfsplus: really remove hfsplus_writepage

The earlier commit to remove hfsplus_writepage only removed it from one of
the aops.  Remove it from the btree_aops as well.

Link: https://lkml.kernel.org/r/20231215200245.748418-9-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>