ubifs: correct the size of nnode in memset

There is a typo in lpt to memset nnode by the
size in sizeof(stuct ubifs_pnode).

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/mkfs.ubifs/lpt.c b/mkfs.ubifs/lpt.c
index f6d4352..6aa0b88 100644
--- a/mkfs.ubifs/lpt.c
+++ b/mkfs.ubifs/lpt.c
@@ -384,7 +384,7 @@
 		goto out;
 	}
 	memset(pnode, 0 , sizeof(struct ubifs_pnode));
-	memset(nnode, 0 , sizeof(struct ubifs_pnode));
+	memset(nnode, 0 , sizeof(struct ubifs_nnode));
 
 	c->lscan_lnum = c->main_first;