Fixes bfs part of #10336. Untested on SATA (don't have a testing drive
to sacrifice) but working fine on SD/MMC.
This requires moving the copy from kernel to userland into the devfs. As
a result the code in the disk drivers becomes a bit simpler.
Also add some documentation for the common ioctls to implement for a
disk device.
Change-Id: Ie84b6a1d293828d33902a64b3c9d4b19aa6eacb1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3640
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>
cef80a1fb7