Merge tag 'efi-2020-04-rc4-5' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-04-rc4 (5)

This series contains bug fixes for the UEFI sub-system:

* report correct variable length in GetNextVariable()
* correct copying direction if freestanding memmove()
* remove const for parameter of GetNextVariableName()
* correct function descriptions

Unit tests are added and adjusted.