iommu: msm: Add standalone support for secure SMMU

Add a configuration option that allows for testing of systems without
a secure environment. When turning on this option all the IOMMUs will
be programmed by the kernel regardless of whether the IOMMU is secure
or not. This allows for early testing during bringup.

Change-Id: I34fde3ba74a69a1d3fb3e5efba3e02cbcc9272d4
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>