arm64: tegra: Add DSU PMUs for Tegra234

Populate the DynamIQ Shared Unit (DSU) Performance Monitor Unit (PMU)
devices for Tegra234 which has one DSU PMU per CPU cluster.

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