feat(xilinx): add wrapper to handle cpu power down req

Firmware sends CPU power down request to TF-A through NOTIFY_CB
callback. It indicates CPU needs to power down.

Add wrapper to handle CPU power down request from firmware
through IPI callback.

Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>
Change-Id: Ic4aff874dd29da057c5ffde1899c7f0e5cdf6733
1 file changed