NFS: Fix a compile error when !defined NFS_DEBUG

We should use the 'ifdebug' wrapper rather than trying to inline
tests of nfs_debug, so that the code compiles correctly when we
don't define NFS_DEBUG.
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4xdr.c

@@ -3440,7 +3440,7 @@ static int decode_pathname(struct xdr_stream *xdr, struct nfs4_pathname *path)
 		status = decode_opaque_inline(xdr, &component->len, &component->data);
 		if (unlikely(status != 0))
 			goto out_eio;
-		if (unlikely(nfs_debug & NFSDBG_XDR))
+		ifdebug (XDR)
 			pr_cont("%s%.*s ",
 				(path->ncomponents != n ? "/ " : ""),
 				component->len, component->data);