Upgrade to Linux 6.0

Why? Improve hardware support, e.g.

• Intel UHD 750: remove the need for the workaround documented in 516a1762
• Graphics cards regressions in Tails 5.8 (#19353): some of these regressions should be fixed by upgrading the kernel; some others will also need a newer Mesa/libdrm stack, which we'll only get by upgrading to Bookworm in Tails 6.0

Process: https://tails.boum.org/contribute/Linux_kernel/

Specific issues to take into account:

• Kernel rfkill interface changes in 5.11 requiring userspace fixes
  • I believe we don't need to do anything, because this only matters when building gnome-settings-daemon against recent kernel headers, while the source tree includes an old version of rfkill.h (without the breaking changes) and the Debian package does not build-depends on the Linux headers nor linux-libc-dev anyway (and even if it did, that would be Bullseye's headers, not 5.11+ ones). -- intrigeri
  • Test results: !996 (comment 201360)
• The 5.17 kernel will require some initrd generator changes for kms drivers
• security things in Linux v5.10
• Bundling these could save us some QA and paperwork:
  • Add randomize_kstack_offset=1 to boot parameters (#19023 - closed)
  • Enable BPF JIT hardening (#19345 - closed)
  • Consider dropping slub_debug=P and page_poison=... (#18858 - closed)