DTS: Add makefile to build DTB/DTBO

Add makefile support to build DTB and DTBO from the
arch/arm64/boot/dts.

This will help to add the DTB/DTBOs for the platform which
are not upstreamed yet.

Change-Id: I1c01de68fbfefb0f6328f3a6a9cc8ff9c8b587cd
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/2700778
GVS: Gerrit_Virtual_Submit

arch/arm64/boot/dts/Makefile

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
+
+objtree = $(srctree)
+
+# Redefine the fixdep command
+cmd_and_fixdep =                                                             \
+	$(cmd);                                                              \
+	$(objtree)/scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
+	rm -f $(depfile)
+
+include $(srctree)/scripts/Makefile.lib
+
+oot-dtstree = $(oottree)/arch/arm64/boot/dts/nvidia
+
+DTB_LIST := $(dtb-y)
+DTBO_LIST := $(dtbo-y)
+dtb-y :=
+dts_makefile=$(foreach d,$(wildcard $1*), $(call dts_makefile,$(d)/,$(2)) $(if $(findstring Makefile,$(d)),$(d)))
+dts_mfiles = $(call dts_makefile, $(oot-dtstree), Makefile)
+
+ifneq ($(dts_mfiles),)
+dts-include :=
+include $(dts_mfiles)
+dtb-y := $(addprefix nvidia/,$(dtb-y))
+dtbo-y := $(addprefix nvidia/,$(dtbo-y))
+endif
+
+DTB_LIST += $(dtb-y)
+DTBO_LIST += $(dtbo-y)
+DTB_OBJS := $(addprefix $(obj)/,$(DTB_LIST))
+DTBO_OBJS := $(addprefix $(obj)/,$(DTBO_LIST))
+
+dtbs: $(DTB_OBJS) $(DTBO_OBJS) FORCE
+
+dtbsclean:
+	find $(oot-dtstree) -name *.dtb | xargs rm -rf
+	find $(oot-dtstree) -name *.dtbo | xargs rm -rf
+	find $(oot-dtstree) -name *.tmp | xargs rm -rf