Include psci.h from tegra platform header
Yatharth Kochar authored
The `plat/nvidia/tegra/include/tegra_private.h` file uses resources
from psci.h (for example, psci_power_state_t) but does not explicitly
include psci.h. This does not currently cause a problem since psci.h
is indirectly included via other headers. However, this may not be
the case in future.

This patch explicitly includes psci.h from tegra_private.h

Change-Id: Ia991147898dbd117c1d3496a95850995a5554c05
ca8b7d51