nfs: add support for large folios

NFS already is void of folio size assumption, so just pass the chunk size
to __filemap_get_folio and set the large folio address_space flag for all
regular files.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>