implemented ROW v4 block IO scheduler

Signed-off-by: zwliew <zhaoweiliew@gmail.com>
block: row: add magic values.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: zwliew <zhaoweiliew@gmail.com>

Conflicts:
	block/row-iosched.c

Change-Id: I7968abafc570edb3a1276a6914a70ac4a696e389