Merge tag 'efi-2020-10-rc6' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-10-rc6

The following UEFI related issues are fixed:

* restore the global data pointer in the RISC-V trap handler
* install EFI_RNG_PROTOCOL only if we have a random number generator
* display human readable string for EFI_RNG_PROTOCOL in efidebug command