Merge tag 'efi-2020-04-rc3' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-04-rc3

* Update the Kconfig description of CONFIG_EFI_RNG_PROTOCOL
* Fix a function comment resolving a warning in 'make htmldocs'