Revert "iommu: arm-smmu: Remove the qcom,skip-init option"

This reverts commit ce4b1cf8.
Required trustzone dependencies are not in place yet. This results
in a bootup crash when mistakenly accessing a context bank belonging
to trustzone.

Change-Id: I3920bad3583eee6e2196a8b34d310a311626369b
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>