The device may be torn down, but the domain should still be valid.  Lets
use that as the tlb flush ops cookie.

Fixes a problem reported in [1]

[1] https://lkml.org/lkml/2020/7/20/104Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 09b5dfff ("iommu/qcom: Use accessor functions for iommu private data")
Link: https://lore.kernel.org/r/20200720155217.274994-1-robdclark@gmail.comSigned-off-by: Joerg Roedel <jroedel@suse.de>