[Yaffs] yaffs2_CheckpointFindNextCheckpointBlock and yaffs_R…

first suppose that you use yaffs inband mode ;
yaffs2_CheckpointFindNextCheckpointBlock get a buffer for read , the buffer
's content maybe
YAFFS_SEQUENCE_CHECKPOINT_DATA, but the block is a * bad *block , so the
buffer 's content
donot changed after read, so yaffs2_CheckpointFindNextCheckpointBlock found
a "*checkpoint *block";
I think the yaffs2_CheckpointFindNextCheckpointBlock should add bad block
detect;