product/rdn2: add System PIK register space declaration

System PIK includes registers for clock control of System PPU,
CMN Kampos Interconnect and DMC. Add the register space declaration
and base address from element management peripheral space.

Change-Id: Ie251919d4ce9dca822400efeb905f7b7d1291800
Signed-off-by: Aditya Angadi <aditya.angadi@arm.com>