[Skiboot] [PATCH] Remove POWER7 and POWER7+ support

[Vaidyanathan Srinivasan]

* Stewart Smith <stewart at linux.ibm.com> [2019-06-03 15:38:34]:

> It's been a good long while since either OPAL POWER7 user touched a
> machine, and even longer since they'd have been okay using an old
> version rather than tracking master.
> 
> There's also been no testing of OPAL on POWER7 systems for an awfully
> long time, so it's pretty safe to assume that it's very much bitrotted.

hmm... So can we document the last working OPAL version for a P7?

I agree that we can remove support because it is not being actively
tested and maintained.  :(

However we should document what version/stable branch should be run on
a P7 to keep the machine working/useful.

--Vaidy