riscv: use atomic CSR bit set/clear operations, refactor

Fix race conditions that cause broken timer interrupts.

Change-Id: I78e13a18d394b1566977e894a1def16a66c9ca5f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5883
Reviewed-by: X512 <danger_mail@list.ru>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

haiku_loader.efi: update for riscv64

* Added MMU page table generation.
* Added optional FDT device detection and passing to kernel.
* Add platform address translation stubs to bios_ia32
to drop EFI ifdefs

Change-Id: I89257c93c84404fd988f621b29f927ed0df3c3b1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4304
Reviewed-by: Jessica Hamilton <jessica.l.hamilton@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>