Revert "move zram to mm"

This reverts commit 10821405d49607cb5c3a9dd9cc83a5d7aabf5842.
sync: allow async waits to be canceled

In order to allow drivers to cleanly handled teardown we need to allow them
to cancel pending async waits.  To do this cleanly, we move allocation of
sync_fence_waiter to the driver calling sync_async_wait().

Change-Id: Ifcd95648be6ec07026d67f810070a4310f099989
Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: Atanas (Tony) Zlatinski <zlatinski@gmail.com>