firmware: xilinx: Add APIs to control node status/power

Add Xilinx ZynqMP firmware APIs to control node status
and power. These APIs allows turning on/off power domain
and setting capabilities of devices present in power domain.

Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Signed-off-by: Jolly Shah <jolly.shah@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>