gpu: host1x: Use SMMU on Tegra124 and Tegra210

Tegra124 and Tegra210 support addressing more than 32 bits of physical
memory. However, since their host1x does not support the wide GATHER
opcode, they should use the SMMU if at all possible to ensure that all
the system memory can be used for command buffers, irrespective of
whether or not the host1x firewall is enabled.

Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>