nfsd: clean up unnecessary temporary variable in nfsd4_decode_fattr

host_err was only used for nfs4_acl_new.
This patch delete it, and return nfserr_jukebox directly.

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>