This patch implements the get_sys_suspend_power_state() handler required by
the PSCI SYSTEM_SUSPEND API. The intent of this handler is to return the
appropriate State-ID field which can be utilized in `affinst_suspend()` to
suspend to system affinity level.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

T210 is the latest chip in the Tegra family of SoCs from NVIDIA. It is an
ARM v8 dual-cluster (A57/A53) SoC, with any one of the clusters being active
at a given point in time.

This patch adds support to boot the Trusted Firmware on T210 SoCs. The patch
also adds support to boot secondary CPUs, enter/exit core power states for
all CPUs in the slow/fast clusters. The support to switch between clusters
is still not available in this patch and would be available later.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>