refactor(sgi): replace references to "SGI"/"sgi" for neoverse_rd

Currently, there are several reference to "SGI" or "sgi" in comments or
as macro prefix within the neoverse_rd directory. As part of the
migration to neoverse_rd, rename all occurences of "SGI/sgi" to
"Neoverse-RD" or the "NRD" prefix accordingly. All references in
comments are rephrased as "Neoverse RD platforms". References in code
are renamed as "NRD"/"nrd" accordingly.

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: Iec195427ff2bee565cb4a325a1a22892be95ae16
diff --git a/plat/arm/board/neoverse_rd/platform/rdn2/platform.mk b/plat/arm/board/neoverse_rd/platform/rdn2/platform.mk
index 3216813..12e7db4 100644
--- a/plat/arm/board/neoverse_rd/platform/rdn2/platform.mk
+++ b/plat/arm/board/neoverse_rd/platform/rdn2/platform.mk
@@ -34,12 +34,12 @@
 
 PLAT_INCLUDES		+=	-I${RDN2_BASE}/include/
 
-SGI_CPU_SOURCES		:=	lib/cpus/aarch64/neoverse_n2.S \
+NRD_CPU_SOURCES		:=	lib/cpus/aarch64/neoverse_n2.S \
 				lib/cpus/aarch64/neoverse_v2.S
 
 PLAT_BL_COMMON_SOURCES	+=	${NRD_COMMON_BASE}/nrd_plat_v2.c
 
-BL1_SOURCES		+=	${SGI_CPU_SOURCES}			\
+BL1_SOURCES		+=	${NRD_CPU_SOURCES}			\
 				${RDN2_BASE}/rdn2_err.c
 
 BL2_SOURCES		+=	${RDN2_BASE}/rdn2_plat.c		\
@@ -50,7 +50,7 @@
 				plat/arm/common/arm_tzc400.c		\
 				plat/arm/common/arm_nor_psci_mem_protect.c
 
-BL31_SOURCES		+=	${SGI_CPU_SOURCES}			\
+BL31_SOURCES		+=	${NRD_CPU_SOURCES}			\
 				${RDN2_BASE}/rdn2_plat.c		\
 				${RDN2_BASE}/rdn2_topology.c		\
 				drivers/cfi/v2m/v2m_flash.c		\