configs/aarch64_efi: bump Linux to 6.10.12

configs/aarch64_efi: bump Linux to 6.10.12

While at it:
- Turn on hashes verification and add a hash for the Linux kernel.
- Linux kernel needs host-python3; add it.
- Convert to `make savedefconfig' format.
- Fix shellcheck warnings in our post-image script and update
  .checkpackageignore.

Signed-off-by: Vincent Stehlé <[email protected]>
Cc: Erico Nunes <[email protected]>
Cc: Dick Olsson <[email protected]>
Cc: Julien Olivain <[email protected]>
Reviewed-by: Julien Olivain <[email protected]>
[Julien: rebased the patch to resolve conflicts with commit
  edc0a6b1a "configs: regenerate all defconfigs"]
Signed-off-by: Julien Olivain <[email protected]>