arm64: dts: rockchip: Add optional node for chasis-type on Anbernic rgxx3

Add optional node for chasis-type defining this device as a handset.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20240325143729.83852-3-macroalpha82@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3566-anbernic-rgxx3.dtsi

@@ -10,6 +10,8 @@
 #include "rk3566.dtsi"
 
 / {
+	chassis-type = "handset";
+
 	chosen: chosen {
 		stdout-path = "serial2:1500000n8";
 	};