Revert "block, cfq: kill cic->key"

This reverts commit f5df127701adb9562fd04d5c67f6d279721f68ab.
Revert "block, cfq: unlink cfq_io_context's immediately"

This reverts commit 6746c8f087a5c128ca039995e28714ed3d9c4088.
Revert "block, cfq: move ioc ioprio/cgroup changed handling to cic"

This reverts commit 7efadcab1c08342e2662ae0b902c5f77b2faa0f5.
Revert "block, cfq: misc updates to cfq_io_context"

This reverts commit ab2f278269d0d79d82357f9ecea99c6b94e8676b.
Revert "block: make ioc get/put interface more conventional and fix race on alloction"

This reverts commit 4bca075d98d0729b8f11a70aa48f5ed7204bc214.
Revert "block: misc ioc cleanups"

This reverts commit 8c22366ce74acb5e32e4273961b706104b6662e1.
Revert "CFQ: move think time check variables to a separate struct"

This reverts commit 94850be12b0b73f7b814917e665b589b32362b24.
Revert "Revert "Add BFQ v5r1 I/O Scheduler""

This reverts commit 35bab13b6f5ea58bb1a98964daeab4780afb942c.