arm64/efi: move EFI init before early FDT processing

arm64/efi: move EFI init before early FDT processing

The early FDT processing is responsible for enumerating the
DT memory nodes and installing them as memblocks. This should
only be done if we are not booting via EFI, but at this point,
we don't know yet if that is the case or not.

So move the EFI init to before the early FDT processing. This involves
making some changes to the way EFI discovers the locations of the
EFI system table and the memory map, since those values are retrieved
from the FDT as well. Instead the of_scan infrastructure, it now uses
libfdt directly to access the /chosen node.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Robert Richter <rrichter@cavium.com>
Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@caviumnetworks.com>