main/linux-postmarketos-qcom-msm8916: upgrade to 5.15 (MR 2632)

- Update to Linux 5.15
- Upstreamed many more patches
- Major rework of CPU core boot: This is now partially handled in lk2nd
  since mainline Linux does not want to support anything except PSCI on arm64.
- Major rework of "-modem" DTB variants. Now all device trees only contain
  the full modem configuration. lk2nd can patch the DTB at runtime to get
  the alternative "no-modem" variant where audio bypasses the modem entirely.
- Rename some Samsung device trees to drop variant suffixes (e.g. *lte/*wifi)
- Lots of other cleanup everywhere
- Probably many other things I forgot :)

Device changes:
  - samsung-gtelwifiue: new device tree
    - eMMC, SD card, USB, Buttons
    - Display (no brightness control yet)
    - Touchscreen
  - gt58: touch keys and some touch fixes
    - Note: Multi-touch seems broken at the moment :<
  - samsung-a2015/samsung-serranove:
    - Battery: Report voltage as uV
    - Touch keys: Allow changing function from userspace

Kernel config changes:
  - Enable required options for AppArmor and IWD

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