[Yaffs] New Yaffs features

Hi All

I've recently added two new features to Yaffs.

1. lost+found directory hiding. This is useful for various situations where
people would rather hide the lost+found directory. This can be selected
through param.hide_lost_n_found.

2. Mixed endian support. Normally - and historically - Yaffs uses the
native CPU endian. However there are occasions when you need to store the
data in a different endian. An example of this would be an ARM-based system
that uses a little endian bootloader, but big endian OS. This feature can
be selected with param.stored_endian. 0 = cpu endian, 1 = little endian, 2
= big endian.

Regards

Charles