Revert 4bc34b1c99eb781a16f5d347b84d8bccc5c9fda7

Change-Id: I74fd0f57050e43ad8417fa75f79e5e547ccb513e
block: introduce the BFQ-v6 I/O sched for 3.0

Change-Id: I460bb927384361568d3c213d7f46f5e5be793a43