Merge tag 'efi-2020-07-rc6' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-07-rc6

Corrections for variable definitions are provided:

* Correct size of secure boot related UEFI variables.
* Do not use int for storing an enum.
* Replace fdt_addr by fdt_size where needed.