feat(xilinx): request cpu power down from reset

Send subsystem restart notification to firmware when TF-A receives
system reset PSCI call. On receiving subsystem restart call, firmware
will send CPU idle callback to TF-A for powering down all cores. Wait
for CPU idle callback from firmware and raise power down request to
all cores after it receives CPU idle callback to power down core.

Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>
Change-Id: I50f417ae228017f38b648740dc90b2e8f1872620
4 files changed