Platform/Sgi: Add Ssdt and Mcfg tables for RD-N2-Cfg1

RD-N2-Cfg1 platform is updated to have two PCIe segments with 32 buses
under each segments. So add new Ssdt and Mcfg tables specific to
RD-N2-Cfg1 platform with two segments each with different ECAM base
addresses and MMIO addresses.

Change-Id: I800de1cc75e9b603aaabd8337acb745d7c0364cf
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Signed-off-by: Vivek Gautam <vivek.gautam@arm.com>