4.14 based tree for LCA

[Joel Stanley]

Hey Tim,

When I cleaned up the litex kernel port, I put a bunch of hacks in the
one commit:

https://github.com/shenki/linux/commit/3c78ac6298fae30a99ac318a6009503b3c126000

- enabling printing of exceptions with litex-uart
- relating to the evbar setup
- mmu hacking
- some save/restoring of registers, I think this is so we preserve
the evbar state?

I want to push a cleaned up branch based on 4.14 to use as our base.
If we could split out a bit of this into "defiantly required", "needs
work" and "just an experiment" that would help. I'd like to make sure
we get the bits sorted out soon, so we can send them upstream in time
for LCA (the merge window will probably open around the time of LCA, so we
want to have them queued up in Stafford's tree before then).

Cheers,

Joel