Platform/Sgi: Helper macros for PPTT Table

Add helper macros for the creation for PPTT table. These macros help
with initializing processor hierarchy node structure, cache type
structure and ID structure.

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