configs/qemu_aarch64_ebbr: tune for workshop

- Remove secure world to have the flash available to U-Boot, for capsule
  update.
- Bump U-Boot and Linux versions.
- Add a script to run the ACS.
- Add a patch to change U-Boot ESRT GUID.
- Generate a signed capsule binary.

Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>