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>

kernel/uart: Clean up uarts, make calling convention consistent

Change-Id: I36ef92ef13edb0b006344db74e9d1b3ae52e0127
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4327
Reviewed-by: X512 <danger_mail@list.ru>
Reviewed-by: Jessica Hamilton <jessica.l.hamilton@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

kernel/arch/debug: implement for riscv64

Change-Id: Iab5cc9ef4059f968bca03683592d1ec1818a26a2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4053
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

riscv64: Fill in more bulk architecture items around libroot/kernel

Change-Id: Ia2a86d8814d06950ea2d2d19d966c642d26f81d6
Reviewed-on: https://review.haiku-os.org/c/1302
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>