Revert "block: don't release queue's sysfs lock during switching elevator"

This reverts commit ee3d84e6.

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

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ia641807b9d11b32ce1d4d71f3f0672f116ecaa0e