refactor(sgi): replace build-option prefix to "NRD"

As of now, CSS_SGI_PLATFORM_VARIANT and CSS_SGI_CHIP_COUNT are the
external build option that "sgi" platforms support. As "sgi" has been
renamed to "neoverse_rd" and the source files have been migrated out of
the css directory, replace the prefix "CSS_SGI" with "NRD".

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: I27989ff42404d823dd2a8cd22ff485497ccb62d4
diff --git a/plat/arm/board/neoverse_rd/platform/rdn1edge/include/platform_def.h b/plat/arm/board/neoverse_rd/platform/rdn1edge/include/platform_def.h
index e17005c..aa8702f 100644
--- a/plat/arm/board/neoverse_rd/platform/rdn1edge/include/platform_def.h
+++ b/plat/arm/board/neoverse_rd/platform/rdn1edge/include/platform_def.h
@@ -38,9 +38,9 @@
  */
 #ifdef __aarch64__
 #define PLAT_PHY_ADDR_SPACE_SIZE	CSS_SGI_REMOTE_CHIP_MEM_OFFSET( \
-						CSS_SGI_CHIP_COUNT)
+						NRD_CHIP_COUNT)
 #define PLAT_VIRT_ADDR_SPACE_SIZE	CSS_SGI_REMOTE_CHIP_MEM_OFFSET( \
-						CSS_SGI_CHIP_COUNT)
+						NRD_CHIP_COUNT)
 #else
 #define PLAT_PHY_ADDR_SPACE_SIZE	(1ULL << 32)
 #define PLAT_VIRT_ADDR_SPACE_SIZE	(1ULL << 32)