refactor(sgi): move neoverse_rd out of css

Currently, neoverse_rd is hosted under the "css" directory. However,
"css" directory is more relevant for hosting css definitions and
corresponding sources. Since neoverse_rd hosts source and header for css
and soc, move neoverse_rd from css to board folder. Consolidate common
sources and headers under neoverse_rd/common. Additionally, group RD-V1,
RD-V1-MC, RD-N2, RD-N1-Edgex2 and SGI-575 within neoverse_rd/platform.
With the changes in this commit, the tree view would look as follows:

plat/arm/board/neoverse_rd/
├── common
│   ├── arch
│   ├── include
│   └── ras
└── platform
    ├── rdn1edge
    ├── rdn2
    ├── rdv1
    ├── rdv1mc
    └── sgi575

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: Iaccc86bc9d415f5c045c834902241fcf3c00277b
diff --git a/plat/arm/board/neoverse_rd/platform/rdn1edge/platform.mk b/plat/arm/board/neoverse_rd/platform/rdn1edge/platform.mk
new file mode 100644
index 0000000..1408351
--- /dev/null
+++ b/plat/arm/board/neoverse_rd/platform/rdn1edge/platform.mk
@@ -0,0 +1,78 @@
+#
+# Copyright (c) 2018-2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+$(warning Platform ${PLAT} is deprecated. Some of the features might not work as expected)
+
+# GIC-600 configuration
+GICV3_IMPL_GIC600_MULTICHIP	:=	1
+
+include plat/arm/board/neoverse_rd/common/nrd-common.mk
+
+RDN1EDGE_BASE		=	plat/arm/board/neoverse_rd/platform/rdn1edge
+
+PLAT_INCLUDES		+=	-I${RDN1EDGE_BASE}/include/
+
+SGI_CPU_SOURCES		:=	lib/cpus/aarch64/neoverse_n1.S
+
+PLAT_BL_COMMON_SOURCES	+=	${NRD_COMMON_BASE}/nrd_plat.c
+
+BL1_SOURCES		+=	${SGI_CPU_SOURCES}			\
+				${RDN1EDGE_BASE}/rdn1edge_err.c
+
+BL2_SOURCES		+=	${RDN1EDGE_BASE}/rdn1edge_plat.c	\
+				${RDN1EDGE_BASE}/rdn1edge_security.c	\
+				${RDN1EDGE_BASE}/rdn1edge_err.c		\
+				drivers/arm/tzc/tzc_dmc620.c		\
+				lib/utils/mem_region.c			\
+				plat/arm/common/arm_nor_psci_mem_protect.c
+
+BL31_SOURCES		+=	${SGI_CPU_SOURCES}			\
+				${RDN1EDGE_BASE}/rdn1edge_plat.c	\
+				${RDN1EDGE_BASE}/rdn1edge_topology.c	\
+				drivers/cfi/v2m/v2m_flash.c		\
+				lib/utils/mem_region.c			\
+				plat/arm/common/arm_nor_psci_mem_protect.c
+
+ifeq (${TRUSTED_BOARD_BOOT}, 1)
+BL1_SOURCES		+=	${RDN1EDGE_BASE}/rdn1edge_trusted_boot.c
+BL2_SOURCES		+=	${RDN1EDGE_BASE}/rdn1edge_trusted_boot.c
+endif
+
+# Enable dynamic addition of MMAP regions in BL31
+BL31_CPPFLAGS		+=	-DPLAT_XLAT_TABLES_DYNAMIC
+
+# Add the FDT_SOURCES and options for Dynamic Config
+FDT_SOURCES		+=	${RDN1EDGE_BASE}/fdts/${PLAT}_fw_config.dts	\
+				${RDN1EDGE_BASE}/fdts/${PLAT}_tb_fw_config.dts
+FW_CONFIG		:=	${BUILD_PLAT}/fdts/${PLAT}_fw_config.dtb
+TB_FW_CONFIG		:=	${BUILD_PLAT}/fdts/${PLAT}_tb_fw_config.dtb
+
+# Add the FW_CONFIG to FIP and specify the same to certtool
+$(eval $(call TOOL_ADD_PAYLOAD,${FW_CONFIG},--fw-config,${FW_CONFIG}))
+# Add the TB_FW_CONFIG to FIP and specify the same to certtool
+$(eval $(call TOOL_ADD_PAYLOAD,${TB_FW_CONFIG},--tb-fw-config,${TB_FW_CONFIG}))
+
+FDT_SOURCES		+=	${RDN1EDGE_BASE}/fdts/${PLAT}_nt_fw_config.dts
+NT_FW_CONFIG		:=	${BUILD_PLAT}/fdts/${PLAT}_nt_fw_config.dtb
+
+# Add the NT_FW_CONFIG to FIP and specify the same to certtool
+$(eval $(call TOOL_ADD_PAYLOAD,${NT_FW_CONFIG},--nt-fw-config,${NT_FW_CONFIG}))
+
+$(eval $(call CREATE_SEQ,SEQ,2))
+ifneq ($(CSS_SGI_CHIP_COUNT),$(filter $(CSS_SGI_CHIP_COUNT),$(SEQ)))
+ $(error  "Chip count for RDN1Edge platform should be one of $(SEQ), currently \
+   set to ${CSS_SGI_CHIP_COUNT}.")
+endif
+
+ifneq ($(CSS_SGI_PLATFORM_VARIANT),0)
+ $(error "CSS_SGI_PLATFORM_VARIANT for RD-N1-Edge should always be 0, \
+     currently set to ${CSS_SGI_PLATFORM_VARIANT}.")
+endif
+
+override CTX_INCLUDE_AARCH32_REGS	:= 0
+
+# Enable the flag since RD-N1-EDGE has a system level cache
+NEOVERSE_Nx_EXTERNAL_LLC		:=	1