nfsd4: encode_rdattr_error cleanup

There's a simpler way to write this.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4xdr.c

@@ -2620,17 +2620,14 @@ nfsd4_encode_dirent_fattr(struct nfsd4_readdir *cd,
 static __be32 *
 nfsd4_encode_rdattr_error(__be32 *p, int buflen, __be32 nfserr)
 {
-	__be32 *attrlenp;
-
 	if (buflen < 6)
 		return NULL;
 	*p++ = htonl(2);
 	*p++ = htonl(FATTR4_WORD0_RDATTR_ERROR); /* bmval0 */
 	*p++ = htonl(0);			 /* bmval1 */
 
-	attrlenp = p++;
+	*p++ = htonl(4);     /* attribute length */
 	*p++ = nfserr;       /* no htonl */
-	*attrlenp = htonl((char *)p - (char *)attrlenp - 4);
 	return p;
 }