[Yaffs] why not add extra header information for mkyaffs2img…

Since extra header information can help lazy loading and boost mount process,
why not add this to mkyaffs2img tool?

Since extra header information is for YAFFS2 only, why not delete code lines
to detect this extra information in yaffs_ScanBackwards and use this directly?

Or is code reserved for backward compatibility?

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Regards, neversetsun