Merge tag 'efi-2019-10-rc1' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Merge tag 'efi-2019-10-rc1' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for v2019.10-rc1

Fix a possible overflow for GUID partition tables.

For some runtime services we only have implementations valid at boottime.
So we replace them when leaving boottime. Move this from
SetVirtualAddressMap() to ExitBootServices() as SetVirtualAddressMap() is
not called by all operating systems. Adjust the Python tests accordingly.

Bump the supported UEFI specification version to 2.8.