Debian-esque config for RBx

[lool]

Hey!

I'd like to build this qcom tree for RBx boards to provide a more fully featured, yet stable, kernel to people evaluating Debian on Qualcomm reference boards, notably RB1, RB3Gen2, and soon RB8/IQ6.

So far, I was either using unmodified Debian binary kernels, but these either don't boot or miss a ton of features, or I was using mainline + defconfig + one config fragment to make systemd-boot happy (CONFIG_EFI_ZBOOT).

Unfortunately, that's not enough for most use cases; e.g. Docker doesn't work (not trivial to find the right configs to set), but also USB audio or video peripherals don't work etc. People really want a Debian-style config!

I'm attaching the result of taking the Debian kernel config from experimental, and applying fixes to boot on RB1 (2290), perhaps this is an useful starting point if we want to carry a reference Debian-esque config in this tree. (Cc: @idlethread)

config-6.15.3+1-arm64_cleaned-up.txt

[lool]

This was missing CONFIG_QCOM_MPM=y and was only working when generating an initramfs from a booted RB1 :)