Platform/Sgi: add ssdt table for non-discoverable IO virt block

For platform that connect non-discoverable devices to IO virtualization
block, add a SSDT table to describe those devices. PL011 UART controller
and PL330 DMA controller are connected to the non-discoverable IO
virtualization block.

Signed-off-by: Vivek Gautam <vivek.gautam@arm.com>
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Change-Id: Ie1501b13a51bb872cdcb8cc49dee0e11631a38b9