NFS: Fix more NFS debug related build warnings

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 69ec9cb..52a1bdb 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -661,8 +661,10 @@
 # undef ifdebug
 # ifdef NFS_DEBUG
 #  define ifdebug(fac)		if (unlikely(nfs_debug & NFSDBG_##fac))
+#  define NFS_IFDEBUG(x)	x
 # else
 #  define ifdebug(fac)		if (0)
+#  define NFS_IFDEBUG(x)
 # endif
 #endif /* __KERNEL */