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/include/platform_def.h b/plat/arm/board/sgi575/include/platform_def.h
index 82a38c5..7cc5366 100644
--- a/plat/arm/board/sgi575/include/platform_def.h
+++ b/plat/arm/board/sgi575/include/platform_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2022, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,8 +9,8 @@
 
 #include <lib/utils_def.h>
 
-#include <sgi_sdei.h>
-#include <sgi_soc_platform_def.h>
+#include <nrd_sdei.h>
+#include <nrd_soc_platform_def.h>
 
 #define PLAT_ARM_CLUSTER_COUNT		U(2)
 #define CSS_SGI_MAX_CPUS_PER_CLUSTER	U(4)