Revert "block: fix race between switching elevator and removing queues"

This reverts commit 6c63a7be.

It breaks the abi and is not needed in Android devices.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ic797c4aef587cf8b8ed62b91e60cb5b236af8036