ARM: dts: stm32: enable stm32mp157's &gpu by default

In the original stm32mp157c.dtsi, the GPU was disabled as some SoC
variants lacked a GPU. We now have separate a dtsi for each SoC
variant and variants without a GPU lack the node altogether.

As we need no board support for using the GPU, enable it by default
and while at it remove the now redundant status = "okay" in existing
board device trees.
Suggested-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157.dtsi

@@ -15,7 +15,6 @@ gpu: gpu@59000000 {
 			clocks = <&rcc GPU>, <&rcc GPU_K>;
 			clock-names = "bus" ,"core";
 			resets = <&rcc GPU_R>;
-			status = "disabled";
 		};
 
 		dsi: dsi@5a000000 {

arch/arm/boot/dts/stm32mp157c-dhcom-som.dtsi

@@ -97,10 +97,6 @@ &dts {
 	status = "okay";
 };
 
-&gpu {
-	status = "okay";
-};
-
 &i2c4 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&i2c4_pins_a>;

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

@@ -126,7 +126,6 @@ &dts {
 
 &gpu {
 	contiguous-area = <&gpu_reserved>;
-	status = "okay";
 };
 
 &i2c4 {

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

@@ -137,7 +137,6 @@ phy0: ethernet-phy@0 {
 
 &gpu {
 	contiguous-area = <&gpu_reserved>;
-	status = "okay";
 };
 
 &i2c1 {