board: rockchip: rk35xx: Add device tree files to MAINTAINERS

Update MAINTAINERS files for RK3566/RK3568/RK3588 boards to include
related device tree files. Also replace space with tabs.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Acked-by: Eugen Hristev <eugen.hristev@collabora.com>
diff --git a/board/anbernic/rgxx3_rk3566/MAINTAINERS b/board/anbernic/rgxx3_rk3566/MAINTAINERS
index 1c0d3fe..6be16a4 100644
--- a/board/anbernic/rgxx3_rk3566/MAINTAINERS
+++ b/board/anbernic/rgxx3_rk3566/MAINTAINERS
@@ -4,3 +4,6 @@
 F:	board/anbernic/rgxx3_rk3566
 F:	include/configs/anbernic-rgxx3-rk3566.h
 F:	configs/anbernic-rgxx3_defconfig
+F:	arch/arm/dts/rk3566-anbernic-rgxx3.dts
+F:	arch/arm/dts/rk3566-anbernic-rgxx3.dtsi
+F:	arch/arm/dts/rk3566-anbernic-rgxx3-u-boot.dtsi