Merge tag 'efi-2020-10-rc1-5' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Merge tag 'efi-2020-10-rc1-5' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-10-rc1 (5)

The series provides bug fixes for:

* crash in OS when accessing UEFI variables
* returning from UEFI fit images to U-Boot
* error handling for variable services provided by OP-TEE
* error handling in EFI_FILE_PROTOCOL.Read()
* missing function documentation

The first patches needed to use intermediate certificates for
secure boot are added. (The rest of the series requires
updating sbsigntool in our CI systems.)

Logging is enabled in the bootefi command.