ARM: dts: stm32: YAML validation fails for STM32MP15 ST Boards

"make dtbs_check" gives following output :
stm32mp157x-xxx.dt.yaml: gpu@59000000: 'contiguous-area' does not match
any of the regexes: 'pinctrl-[0-9]+'
        From schema: Documentation/devicetree/bindings/gpu/vivante,gc.yaml

Solve this trouble for STM32MPU Boards :
- stm32mp157c-ed1
- stm32mp157x-dkx

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp157c-ed1.dts

@@ -69,11 +69,6 @@ retram: retram@38000000 {
 			reg = <0x38000000 0x10000>;
 			no-map;
 		};
-
-		gpu_reserved: gpu@e8000000 {
-			reg = <0xe8000000 0x8000000>;
-			no-map;
-		};
 	};
 
 	sd_switch: regulator-sd_switch {
@@ -140,10 +135,6 @@ &dts {
 	status = "okay";
 };
 
-&gpu {
-	contiguous-area = <&gpu_reserved>;
-};
-
 &hash1 {
 	status = "okay";
 };

arch/arm/boot/dts/stm32mp15xx-dkx.dtsi

@@ -59,11 +59,6 @@ retram: retram@38000000 {
 			reg = <0x38000000 0x10000>;
 			no-map;
 		};
-
-		gpu_reserved: gpu@d4000000 {
-			reg = <0xd4000000 0x4000000>;
-			no-map;
-		};
 	};
 
 	led {
@@ -157,10 +152,6 @@ phy0: ethernet-phy@0 {
 	};
 };
 
-&gpu {
-	contiguous-area = <&gpu_reserved>;
-};
-
 &hash1 {
 	status = "okay";
 };