Merge tag 'efi-2020-07-rc4' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-07-rc4

This patch series addresses the following issues:

* allow compiling with clang
* add missing function descriptions to the HTML documentation
* simplify the validation of UEFI images
* validate load options in the UEFI boot manager

In a preparatory patch a structure definition is moved.