refactor(sgi): update source path in script for "sgi platforms"

As part of the move from "sgi", Trusted Firmware source files for "sgi
platforms" have been regrouped under "plat/arm/board/neoverse_rd".
Therefore, update the source path for "sgi platforms" with the new path
at all relevant places where they are referenced.

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: I1869db963574c91f647d15a3857e00a4a5123f09
2 files changed