In the prior change we added block-device-[mbr|gpt|efi] elements to
create appropriate disk-layouts.
This adds an environment flag to each so the bootloader can install
the right thing. The EFI install path is updated to work with this
(this part a copy of I572937945adbb5adaa5cb09200752e323c2c9531)
We do some basic sanity checking in the block-device elements;
e.g. mbr is not suitable for aarch64, and efi is not suitable for
power.
This updates the bootloader to install EFI where appropriate
Co-Authored-By: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Change-Id: Ib80acbfd9a12efd976c3fa15a5d1081eb0799305
