linux: Update version from 5.1.1 to 5.1.2

[Announcement][1]:

> I'm announcing the release of the 5.1.2 kernel.
>
> All users of the 5.1 kernel series must upgrade.  Well, kind of, let me rephrase that...
>
> All users of Intel processors made since 2011 must upgrade.
>
> Note, this release, and the other stable releases that are all being
> released right now at the same time, just went out all contain patches
> that have only seen the "public eye" for about 5 minutes.  So be
> forwarned, they might break things, they might not build, but hopefully
> they fix things.  Odds are we will be fixing a number of small things in
> this area for the next few weeks as things shake out on real hardware
> and workloads.  So don't think you are done updating your kernel, you
> never are done with that :)
>
> As for what specifically these changes fix, I'll let the tech news sites
> fill you in on the details.  Or go read the excellently written Xen
> Security Advisory 297:
> 	https://xenbits.xen.org/xsa/advisory-297.html
> That should give you a good idea of what a number of people have been
> dealing with for many many many months now.
>
> Many thanks goes out to Thomas Gleixner for going above and beyond to do
> the backports to the 5.1, 5.0, 4.19, and 4.14 kernel trees, and to Ben
> Hutchings for doing the 4.9 work.  And of course to all of the
> developers who have been working on this in secret and doing reviews of
> the many different proposals and versions of the patches.
>
> As I said before just over a year ago, Intel once again owes a bunch of
> people a lot of drinks for fixing their hardware bugs, in our
> software...
>
> Anyway, as usual, the updated 5.1.y git tree can be found at:
> 	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-5.1.y
> and can be browsed at the normal kernel.org git web browser:
> 	https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary

[1]: https://lkml.org/lkml/2019/5/14/651