NFSv4: Fix an NFSv4 mount regression

The helper nfs_fs_mount() will always call nfs4_try_mount with the
mount_info->fill_super argument pointing to nfs_fill_super, which is
NFSv2/v3 only.
Fix is to have nfs4_try_mount replace it with nfs4_fill_super.

The regression was introduced by commit c40f8d1d (NFS: Create a common
fs_mount() function)

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/super.c

@@ -2860,6 +2860,8 @@ static struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 
 	dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 
+	mount_info->fill_super = nfs4_fill_super;
+
 	export_path = data->nfs_server.export_path;
 	data->nfs_server.export_path = "/";
 	root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,