[PATCH] ubi: Fix early logging

[Joe Perches]

From:	Richard Weinberger <richard at nod.at>
[]
> We must not use ubi_* log functions before the ubi_device
> struct is initialized.
> And while we are here, define a sane pr_fmt and add new lines to
> existing pr_* calls.

I think it'd be better to use and extend the patch I sent
for this problem.

https://patchwork.ozlabs.org/patch/587057/

Add a state check of the ubi pointer in the ubi_<level>
functions and do the right thing there.