patches: dwarves: Zero-initialize struct cu in cu__new() to prevent incorrect BTF types

Add the dwarves: Zero-initialize struct cu in cu__new() to prevent incorrect BTF types from upstream.

Without this patch, pahole is creating a lot of BTF deduplication, significantly increasing the kernel Image size. The arm64 kernel went from 30MB to 44MB without any significant config changes.

This should fix the rpi-4b boot issue caused by the kernel being too big (u-boot only allows up to 36MB): https://lava.collabora.dev/scheduler/job/10416215#L8739

For more details, the issue was discussed here (report) and here (fix)

This delta should be dropped when updating to dwarves 1.25