Revert "[LINARO] workqueue: Add system wide power_efficient workqueues"

This reverts commit b9eed4e50e35ec62c3605a34e4513ece5a640931.
Revert "[LINARO] block: queue work on power efficient wq"

This reverts commit 15700c4f3d033efdb8ab7dc23cf14587fd2c9812.