arm/efi: Switch to arm64 linux loader

arm/efi: Switch to arm64 linux loader

The arm64 and arm linux kernel EFI-stub support presents pretty much
identical interfaces, so the same linux loader source can be used for
both architectures.

Switch 32-bit ARM UEFI platforms over to the existing EFI-stub aware
loader initially developed for arm64.

This *WILL* stop non-efistub Linux kernels from booting on arm-efi.

Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>