Merge branch '2022-04-19-assorted-updates'

- Migrate CONFIG_SYS_MEM_TOP_HIDE to Kconfig, IOMUX bugfix, 2 BTRFS
bugfixes, update .gitignore and .mailmap files, aspeed GPIO bugfix,
image-fit and squashfs code cleanups, enable EXT4 and ISO partitions on
DeveloperBox.
- populate u-boot,bootconf under /chosen, see
  https://github.com/devicetree-org/dt-schema/pull/71 for corresponding
  change