Merge tag 'efi-2021-04-rc2' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2021-04-rc2

Bug fixes:

* do not allow creating of files with filenames on FAT file system
* install UEFI System Partition GUID on ESP handle
* in dtbdump.efi test tool use GUID to find ESP handle

Documentation:

* man-page for load command
* describe end of life of plat_auto

diff --cc doc/driver-model/design.rst
Simple merge