arm64: tegra: Select ARM_GIC_PM

Enable ARM_GIC_PM for 64-bit Tegra devices. This is required to ensure
that the driver gets built into kernel and helps to register the AGIC
device when enabled in DT.

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