plat: xilinx: versal: Add support of register notifier

Add support of register notifier.

Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Change-Id: I41ef4c63abcc9aee552790b843adb25a5fd0c23e
4 files changed