Merge tag 'efi-2020-10-rc1-4' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-10-rc1 (4)

Improvements for the UEFI subsystem include:

* support for read-only TEE-backed variables
* allow to compile PK, KEK, db, dbx fixed values into U-Boot
* bug fixes

Python testing related changes comprise:

* enable 'bootefi hello' for better test coverage
* remove SKIP messages in UEFI Python tests

The fitupd command is dropped.
Build errors for the lsblk command are fixed.