* Set SUNXI_AMEND_DTB=1, so we don't need to add the CPU idle states
  with an out-of-tree kernel patch to the dtb (as it was done with
  megi's orange-pi tree until 2022-05-21 which we use for
  linux-postmarketos-allwinner).
* Set SUNXI_SETUP_REGULATORS=0, so it doesn't break ethernet on the
  Orange Pi 3 and similar boards.

Related: https://trustedfirmware-a.readthedocs.io/en/latest/plat/allwinner.html
Related: https://github.com/ARM-software/arm-trusted-firmware/blob/master/plat/allwinner/common/allwinner-common.mk
Related: https://gitlab.com/postmarketOS/pmaports/-/merge_requests/3263