Merge tag 'efi-2019-10-rc2' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for v2019.10-rc2

With this pull request a workaround for GRUB on 32bit ARM is re-enabled
and made customizable. Without the patch booting on ARM 32bit with GRUB
prior to version 2.04 or with a cache which is not managed via CP15
fails.

Further work will be needed to achieve a UEFI compliant cache handling.
According to the UEFI spec all caches except those that cannot be
managed via CP15 should be enabled.

An implementation of the ConvertPointer() runtime service is provided.

efi_crt0 is always rebuild to avoid having to call 'make mrproper' when
switching architectures.