platform/rdn2*: move to pcie hierarchy file to platform folder

In order to keep the pcie hierarchy file specific to rdn2 and rdn2cfg1
platforms, create the example pcie hierarchy file within the each
platform folders.

Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Change-Id: I8e68630ebfaf26f7b9f41ee3c5d6927c4b53d119