[Yaffs] Adding Sergey's patch to CVS

Hi all

I have added Sergey's patch to CVS because it is a valuable thing to have and
I think it is better in CVS than floating around the list. It is not the
original patch, but is slightly modified.

I have used this on a couple of boards now, and a few others have also
reported that this fixes their problems. I found that due to some issues in
mtd, Sergey's patch would not work straight up on the boards I tested, but
needed a tweak to disable one of the mtd access modes (the "if ( 0 &&") in
approx line 170.

The patched yaffs_mtdif2.c is not in the main code, but is in the patches
subdirectory.

Despite our differences of opinion on various issues, I would like to thank
Sergey for providing the patch.

Charles