Merge tag 'efi-2020-04-rc4' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-04-rc4

UEFI spec 2.8 errata A replaces the RuntimeServicesSupported variable
defined in UEFI spec 2.8 by the configuration table
EFI_RT_PROPERTIES_TABLE. So let's follow suit.