NFSD: Replace READ* macros in nfsd4_decode_destroy_session()

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4xdr.c

@@ -1678,11 +1678,7 @@ static __be32
 nfsd4_decode_destroy_session(struct nfsd4_compoundargs *argp,
 			     struct nfsd4_destroy_session *destroy_session)
 {
-	DECODE_HEAD;
-	READ_BUF(NFS4_MAX_SESSIONID_LEN);
-	COPYMEM(destroy_session->sessionid.data, NFS4_MAX_SESSIONID_LEN);
-
-	DECODE_TAIL;
+	return nfsd4_decode_sessionid4(argp, &destroy_session->sessionid);
 }
 
 static __be32