[Yaffs] Lazy loading speedup

Hi all

There has not been much feedback on lazy loading speed ups, but what I've
heard is quite promising. I have had one person say that they got a 22 second
mount with lazy loading when they were getting 36 seconds previously. This
was on a partition with a few hundred files. That's quite a lot better than I
was expecting.

Lazy loading saves the time that would normally be taken by reading object
info, so the amount of time saved will be approx. proportional to the number
of objects (files, directories, etc) in the system - including deleted stuff
not yet garbage collected.

-- Charles