riscv64/smp: Implement multi-processor support

* Working under qemu smp 1,2+
* Working on SiFive Unmatched
* x86_64 efi not broken by smp_boot_other_cpus change

Change-Id: I32ebc17913e46ed082be9ade8f56448bbf12f16e
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4705
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

system/kernel: Rework uart management

Change-Id: I6cb31760519c8ba4542d217d6e68439602eda558
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4356
Reviewed-by: Jessica Hamilton <jessica.l.hamilton@gmail.com>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

riscv: fix typo frequrency -> frequency

Change-Id: I7a2ed220ad96a9b18bff3ac5c115592c8ba87d89
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4334
Reviewed-by: Axel Dörfler <axeld@pinc-software.de>

kernel/arch/platform: implement for riscv64

Change-Id: Id1839ef39d927e6a2017c8b8ac3482d9eeb00fa1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4059
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

kernel: update arch headers for riscv64

Change-Id: Iaf1c253745412614f7e4a30019d96483cb0d3a12
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4310
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

kernel: riscv64 patches

Change-Id: I8ebcbaa395cbccb50af08fd2f1b049b5cbb949c7
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3883
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Reviewed-by: X512 <danger_mail@list.ru>

EFI: Make our haiku_loader architecture agnostic

* This is the bulk of the work. Anything else should be
minor cleanups and tweaking.
* riscv64 isn't a viable EFI platform yet.. just acting
as a stand-in to test a non-x86 EFI haiku_loader

Change-Id: Ib03de81e2b562e693987b86d7b4318209fb1c792
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2256
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

kernel/riscv64: Add missing kernel_arg ranges to get build going.

Change-Id: Idf549a5e4d01e6dc8949ec1252296337e5ef970c
Reviewed-on: https://review.haiku-os.org/c/1380
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

headers/riscv64: Implement basic arch headers

Change-Id: I6bfbacb61eae84ffebc30c2565683348d684d88f
Reviewed-on: https://review.haiku-os.org/c/1063
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>