boot/efi/arm: add debug logs for initial CPU state

Change-Id: I08df563ef6967f5f9734bbe11ac643c3b68f504f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5151
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

boot/arm: move system_time and spin to platform

Add fake implementation for system_time()
Implement spin() using EFI boot services

Change-Id: Ib69b851780bd03624ce4e19d725dd319f6640601
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4964
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>

efi: Refactor CPU code to be arch-specific

* Migrate some platform agnostic architecture code into
boot/arch from efi/arch. This helps to avoid conflicts
between kernel and boot sources as well.
* Conflicts between arch_cpu in efi and kernel code means
bootcode really should *never* directly use kernel arch
headers. (other platforms don't, which is why they don't
have this same issue)
* We carefully thread any needed kernel headers (namely
assembly helper macros) into the bootloader headers without
mixing in the whole conflicting kernel/arch headers.
* ARM now properly get its cpu init code called, and we
progress further into the EFI bootloader.

Change-Id: If67ec9758b5ce68563ebd9eb45d5196401911c67
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2975
Reviewed-by: waddlesplash <waddlesplash@gmail.com>