dts, arm64: Move dts files to vendor subdirs

Moving dts files to vendor subdirs.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Robert Richter <rrichter@cavium.com>
diff --git a/arch/arm64/boot/dts/Makefile b/arch/arm64/boot/dts/Makefile
index 77130bd..e8efc8f 100644
--- a/arch/arm64/boot/dts/Makefile
+++ b/arch/arm64/boot/dts/Makefile
@@ -1,6 +1,6 @@
-dtb-$(CONFIG_ARCH_THUNDER) += thunder-88xx.dtb
-dtb-$(CONFIG_ARCH_VEXPRESS) += rtsm_ve-aemv8a.dtb foundation-v8.dtb
-dtb-$(CONFIG_ARCH_XGENE) += apm-mustang.dtb
+dts-dirs += apm
+dts-dirs += arm
+dts-dirs += cavium
 
 always		:= $(dtb-y)
 subdir-y	:= $(dts-dirs)