[Merge] ~xnox/grub:arm64-fdt+tpm into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu

[Julian Andres Klode]

Cherry-picked into into Ubuntu branch as-is, and Debian with some rewording. Kind of at the start of the 2.12 rebase of the former.
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https://code.launchpad.net/~xnox/grub/+git/grub/+merge/438154
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~xnox/grub:arm64-fdt+tpm into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu.