nfs: don't bother setting/restoring export_path around do_nfs_root_mount()

nothing in it will be looking at that thing anyway
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4super.c

@@ -233,12 +233,10 @@ struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 	dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 
 	export_path = data->nfs_server.export_path;
-	data->nfs_server.export_path = "/";
 	root_mnt = nfs_do_root_mount(
 			nfs4_create_server(mount_info, &nfs_v4),
 			flags, mount_info,
 			data->nfs_server.hostname);
-	data->nfs_server.export_path = export_path;
 
 	res = nfs_follow_remote_path(root_mnt, export_path);
 
@@ -271,12 +269,10 @@ static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 		return ERR_PTR(-ENOMEM);
 
 	export_path = data->mnt_path;
-	data->mnt_path = "/";
 	root_mnt = nfs_do_root_mount(
 			nfs4_create_referral_server(mount_info.cloned,
 						    mount_info.mntfh),
 			flags, &mount_info, data->hostname);
-	data->mnt_path = export_path;
 
 	res = nfs_follow_remote_path(root_mnt, export_path);
 	dprintk("<-- nfs4_referral_mount() = %d%s\n",