Merge tag 'efi-2019-07-rc4-2' of git://git.denx.de/u-boot-efi

Pull request for UEFI sub-system for v2019.07-rc4-2

Support for managing the non-volatile attribute of UEFI variables
is added though we do not have a backend for persistence yet.

Error messages for changes of UEFI variables are provided.

UEFI boottime service implementations are corrected.