UBIFS: fix oops on error path in read_pnode

Thanks to coverity which spotted that UBIFS will oops if 'kmalloc()'
in 'read_pnode()' fails and we dereference a NULL 'pnode' pointer
when we 'goto out'.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: stable@kernel.org

fs/ubifs/lpt.c

@@ -1270,10 +1270,9 @@ static int read_pnode(struct ubifs_info *c, struct ubifs_nnode *parent, int iip)
 	lnum = branch->lnum;
 	offs = branch->offs;
 	pnode = kzalloc(sizeof(struct ubifs_pnode), GFP_NOFS);
-	if (!pnode) {
-		err = -ENOMEM;
-		goto out;
-	}
+	if (!pnode)
+		return -ENOMEM;
+
 	if (lnum == 0) {
 		/*
 		 * This pnode was not written which just means that the LEB