[mako] Update kernel to 4.12

Created by: mmaret

John Stultz worked on mainlining the Nexus 7 (https://plus.google.com/u/0/111524780435806926688/posts/fkQ1BMjNNcn, https://plus.google.com/111524780435806926688/posts/7gNfnn4tpqe) and got cool results with even the Wifi working. I think that he keeps his work updated as his kernel branch is based on the kernel 4.12 https://git.linaro.org/people/john.stultz/flo.git/log/?h=flo-WIP

Nexus 4 and Nexus 7 are said to be similar so may be it's easier to try this nearly upstream kernel instead of the 3.4 from Lineage ?

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