FAT FS enhancements

[David Brennan]

Thanks.

Andrew Lunn wrote:

>>>>Attached is the next round:
>>>>        
>>>>
>
>Great. I've made a few minor changes:
>
>cyg/fs/fat/fatfs.h -> cyg/fs/fat.h
>  
>
That was the directory you had told me to put it in. I did not think 
that was correct. Just following directions.

>open() now returns EACCES which POSIX says it should do.
>  
>
You did not change fileio1.c test-case to match this change.

Dave