Platform/Sgi: Add CPU container for RD-V1 quad-chip platform

The RD-V1 quad-chip platform is composed of four RD-V1 platforms
connected over a coherent link. Each chip has four CPU cores with each
core contained in a minimal cluster logic. Update the processor device
entries accordingly in the DSDT ACPI table by moving each of the
processor device entries into a separate processor container devices.

Signed-off-by: Pranav Madhu <pranav.madhu@arm.com>
Reviewed-by: Thomas Abraham <thomas.abraham@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>