[patch] UBIFS: Add cryptographic functionality when a key is passed to the compress / decompress functions

[Joel Reardon]

>
> I guess I was a little confused WRT iv vs cryptokey. Anyway, I thought
> you just use UBIFS_CRYPTO_KEYSIZE for all of this, why not to just use
> the constant in this function? Why passing the length as an argument?
>

There's no actually reason... in my head, if I have a char buffer then the
next parameter is its length. I'll change it so the comments discuss the
length of the buffer.