arm64: dts: rockchip: rename thermal subnodes for rk3368

A test with the command below gives for example this error:
/arch/arm64/boot/dts/rockchip/rk3368-px5-evb.dt.yaml:
thermal-zones: 'cpu', 'gpu' do not match any of the regexes:
'^[a-zA-Z][a-zA-Z0-9\\-]{1,12}-thermal$', 'pinctrl-[0-9]+'

Make the rk3368 thermal subnode names in line with the rest of
the Rockchip dts files. Add a label and rename them so that it ends
with "-thermal"

make ARCH=arm64 dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/
thermal/thermal-zones.yaml
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20210117150953.16475-2-jbx6244@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3368.dtsi

@@ -400,7 +400,7 @@ uart4: serial@ff1c0000 {
 	};
 
 	thermal-zones {
-		cpu {
+		cpu_thermal: cpu-thermal {
 			polling-delay-passive = <100>; /* milliseconds */
 			polling-delay = <5000>; /* milliseconds */
 
@@ -444,7 +444,7 @@ map1 {
 			};
 		};
 
-		gpu {
+		gpu_thermal: gpu-thermal {
 			polling-delay-passive = <100>; /* milliseconds */
 			polling-delay = <5000>; /* milliseconds */