jfs: Convert metapage_writepage to metapage_write_folio

Implement writepages rather than writepage by using write_cache_pages()
to call metapage_write_folio().  Use bio_add_folio_nofail() as we know
we just allocated the bio.  Replace the call to SetPageError (which
is never checked) with a call to mapping_set_error (which ... might be
checked somewhere?)

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>