rdfremontcfg1: add pcie hierarchy files

Map the heirarchy as per following
x1 - defualt
x20 - example_pcie_hierarchy_1.json
x21 - example_pcie_hierarchy_2.json
x4 - example_pcie_hierarchy_3.json
x8 - example_pcie_hierarchy_4.json

x1 is give default as it is cofigured fist in the sequence.

Signed-off-by: Nishant Sharma <nishant.sharma@arm.com>