main/linux-postmarketos-qcom: update to kernel v5.2 (!514)

Update to the 5.2 kernel plus my patches for the Nexus 5 display that
will also work for other msm8974-based systems:
https://github.com/masneyb/linux/commits/v5.2-nexus5-display. There's
currently 25 extra patches on top of 5.2:

- The first 9 patches after the 5.2 commit are currently in 5.3rc1 and
  were back ported to 5.2. All of these patches have 'Commit XXX
  upstream.' messages in the commit message.
- The next 9 patches are for ocmem support and some msm display fixes. I
  expect that these will be merged upstream for 5.4rc1.
- The remaining 7 patches are still not suitable to send upstream.

[ci:skip-build]: already built successfully in CI