imx6: aristainetos: add device tree from linux

Add device trees from Linux in preparation for driver model
conversions.

device tree files taken from Linux:
71ae5fc87c34: "Merge tag 'linux-kselftest-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest"

and added SPDX license identifier.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/board/aristainetos/MAINTAINERS b/board/aristainetos/MAINTAINERS
index 7e9f38d..91c8ae0 100644
--- a/board/aristainetos/MAINTAINERS
+++ b/board/aristainetos/MAINTAINERS
@@ -4,3 +4,6 @@
 F:	board/aristainetos/
 F:	include/configs/aristainetos2.h
 F:	configs/aristainetos2_defconfig
+F:	arch/arm/dts/imx6dl-aristainetos2_4.dts
+F:	arch/arm/dts/imx6dl-aristainetos2_7.dts
+F:	arch/arm/dts/imx6qdl-aristainetos2.dtsi