Revert "BFQ: Change elevator_type to type"

This reverts commit e50ecd490a3209b7bb35df7c8dfb6e36f08fbfb3.
Revert "block: remove aliased requests from BFQ"

This reverts commit 927a77cf7f4a31b7ea3536316d5675c414f9957d.
Revert "block: introduce the BFQ-v5r1 I/O sched for 3.0"

This reverts commit d939f3a42c8ee5dc59aaf1cf6e7963527c6d549c.
Revert "block: cgroups, kconfig, build bits for BFQ-v5r1-3.0"

This reverts commit a7142593b52fc36f7456169f30eb47f7ea367dbd.
Revert "block: prepare I/O context code for BFQ-v5r1 for 3.0"

This reverts commit e47be248d86b7b444c72127c2dc7978f6ed506f1.