refactor(sgi): move from "sgi" to "neoverse_rd"

Currently, reference design platforms such as RD-N2, RD-N1-Edge,
RD-V1-MC, RD-V1 and SGI-575 utilize "css/sgi" as the common source
directory. The "sgi" prefix originated from the System Guidance for
Infrastructure (SGI) and was initially associated with the SGI-575
platform. However, subsequent platforms released were under the Neoverse
Reference Design product name.

To align with the Neoverse Reference Design nomenclature, rename the
common source directory from "css/sgi" to "css/neoverse_rd" and update
all file prefixes from "sgi" to "nrd."

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: I3dcbb31b9ab202e82caf25218ba33c520dcea4e4
diff --git a/plat/arm/board/sgi575/platform.mk b/plat/arm/board/sgi575/platform.mk
index 2f2bf73..2a03b1d 100644
--- a/plat/arm/board/sgi575/platform.mk
+++ b/plat/arm/board/sgi575/platform.mk
@@ -1,12 +1,12 @@
 #
-# Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2018-2024, Arm Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
 $(warning Platform ${PLAT} is deprecated. Some of the features might not work as expected)
 
-include plat/arm/css/sgi/sgi-common.mk
+include plat/arm/css/neoverse_rd/nrd-common.mk
 
 SGI575_BASE		=	plat/arm/board/sgi575
 
@@ -14,7 +14,7 @@
 
 SGI_CPU_SOURCES		:=	lib/cpus/aarch64/cortex_a75.S
 
-PLAT_BL_COMMON_SOURCES	+=	${CSS_ENT_BASE}/sgi_plat.c
+PLAT_BL_COMMON_SOURCES	+=	${CSS_ENT_BASE}/nrd_plat.c
 
 BL1_SOURCES		+=	${SGI_CPU_SOURCES}			\
 				${SGI575_BASE}/sgi575_err.c