Kernel: T5499: update arm64 kernel configuration to v6.6.15

[Schamper]

Change Summary

As a follow-up/improvement to #421, I've meticulously compared the default Debian arm64 configuration with the VyOS x86 configuration and cherry-picked all of the changes made by Debian (for a proper working arm64 kernel) and VyOS (for all the specific VyOS tweaks). I'm not a kernel developer by any means so I may have missed one or two, but I do believe I got all the important bits.

I've verified that the resulting kernel (with some other small tweaks to make the rest of the build work) results in a stable VyOS Sagitta that has been running for a few weeks now in a VMware VM on Apple Sillicon. I specifically built a Sagitta ISO because that's what I intend to run long-term. I expect the current branch to also run fine.

If the team is interested, the changes required to get a happy Sagitta on arm64 mostly boils down to some package compilations for arm64 to be added to the sagitta package mirror, and a backport of vyos/vyos-1x@37bd574.

The kernel builds in a few minutes on an M3 Max, I don't currently have access to a x86 instance that's similarly specced as the build server to compare build times under QEMU. I unfortunately also don't have access to other ARM hardware to test.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5499

Component(s) name

Kernel

Proposed changes

How to test

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[c-po]

Can we close #421?