NFSv4: Fix Oops in nfs4_create_referral_server

The filehandle that is passed into nfs4_create_referral_server is
not initialised. The expectation is that nfs4_create_referral_server will
initialise it, and return it to the caller.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 28108c8..89da0a3 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1044,7 +1044,7 @@
 		nfs4_fill_super(s);
 	}
 
-	mntroot = nfs4_get_root(s, data->fh);
+	mntroot = nfs4_get_root(s, &mntfh);
 	if (IS_ERR(mntroot)) {
 		error = PTR_ERR(mntroot);
 		goto error_splat_super;