nilfs2: use iget5_locked to get inode

This uses iget5_locked instead of iget_locked so that gc cache can
look up inodes with an inode number and an optional checkpoint number.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 51576b4..f3a00a3 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -155,6 +155,7 @@
 		return NULL;
 	ii->i_bh = NULL;
 	ii->i_state = 0;
+	ii->i_cno = 0;
 	ii->vfs_inode.i_version = 1;
 	nilfs_btnode_cache_init(&ii->i_btnode_cache, nilfs->ns_bdi);
 	return &ii->vfs_inode;