Revert "FROMGIT: iommu/arm-smmu: Don't bypass pinned stream mappings"

This reverts commit 792c2bf3.

This patch relies on a failed upstream submission [0].  Bjorn also
reports that Qualcomm solve these types of issues using the upstream
solution in their downstream kernel now [1].

[0] https://lore.kernel.org/r/20191226221709.3844244-4-bjorn.andersson@linaro.org
[1] https://lore.kernel.org/linux-arm-kernel/YKxuynamQBTrNksO@yoga/



Suggested-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I9b213d5b6d95c979b4b33cb3ec7e25c10042e8c8