powerpc/book3s: Fix flush_tlb cpu_spec hook to take a generic argument.

[Benjamin Herrenschmidt]

On Fri, 2014-10-03 at 17:36 +1000, Michael Ellerman wrote:
> It seems that the only detail we are abstracting here is that power7 has 128
> TLB sets and power8 has 512. Is that right?

Today ...

> It seems like a lot of code to deal with that one detail.
> 
> I guess the other thing it does is cur_cpu_spec->flush_tlb() is only
> implemented on power7 and power8, ie. not power6. But it seems that the two
> callers can only ever run on power7/power8 anway.
> 
> So couldn't we just do:
>  - add the number of tlb_sets to cpu_spec
>  - use that in flush_tlb()

Provided the form of tlbiel we use remains ... things are different from
embedded for example. I've asked Mahesh to add this hook with the idea
somewhat to migrate existing/older code to use it as well, and on older
chips or embedded the TLB flush is quite different.

Cheers,
Ben.