Revert "dm: fix deadlock when swapping to encrypted device"

This reverts commit 5c5bb514.

It breaks the abi and is nothing that is needed for any Android devices.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I6f14268eae3250b096ed9e12c5d66bec8935dc11