iommu/tegra: Setup aperture

Each address space in the Tegra SMMU provides 4 GiB worth of addresses.

Cc: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>