Merge tag 'efi-2022-04-rc1-2' of https://source.denx.de/u-boot/custodians/u-boot-efi

Pull request for efi-2022-04-rc1-2

Documentation:

* describe printf() format codes

UEFI

* enable more algorithms for UEFI image verification, e.g. SHA256-RSA2048

General

* simplify printing short texts for GUIDs
* provide a unit test for printing GUIDs