arm: total_compute: depend on TF-A for hardware description

arm: total_compute: depend on TF-A for hardware description

On Total Compute, TF-A passes the info via DT binding for the hardware
description - includes the serial, memory, and arm_ffa nodes.

This commit initializes the fdt base address based on the passed the
register x1.

The similar implementation has already been done for the raspberry pi,
so borrow a lot of it.

Co-developed-by: Jackson Cooper-Driver <jackson.cooper-driver@arm.com>
Signed-off-by: Jackson Cooper-Driver <jackson.cooper-driver@arm.com>
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Signed-off-by: Leo Yan <leo.yan@arm.com>