NFSD: Add POSIX ACL file attributes to SUPPATTR bitmasks

NFSD: Add POSIX ACL file attributes to SUPPATTR bitmasks

Now that infrastructure for NFSv4 POSIX draft ACL has been added
to NFSD, it should be safe to advertise support to NFS clients.

NFSD_SUPPATTR_EXCLCREAT_WORD2 includes NFSv4.2-only attributes,
but version filtering occurs via nfsd_suppattrs[] before this
mask is applied, ensuring pre-4.2 clients never see unsupported
attributes.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>