boards: st: fix STM32F3 boards DTS files coding style

Fix board DTS coding style issues to prevent they spread when a	new
board is introduced and used this DTS as example start point.

Issues addressed from Zephyr devicetree style guidelines [1]:
- Indent with tabs.
- Don’t insert empty lines before a dedenting };.
- Insert a single empty line to separate nodes at the same hierarchy level.

No functional change.

Link: https://docs.zephyrproject.org/latest/contribute/style/devicetree.html [1]
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>

boards/st/nucleo_f302r8/nucleo_f302r8.dts

@@ -24,6 +24,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_2: led_2 {
 			gpios = <&gpiob 13 GPIO_ACTIVE_HIGH>;
 			label = "User LD2";
@@ -32,6 +33,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "User";
 			gpios = <&gpioc 13 GPIO_ACTIVE_LOW>;

boards/st/nucleo_f303k8/nucleo_f303k8.dts

@@ -22,6 +22,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_3: green_led_3 {
 			gpios = <&gpiob 3 GPIO_ACTIVE_HIGH>;
 			label = "LD3";
@@ -29,6 +30,7 @@
 	};
 	pwmleds {
 		compatible = "pwm-leds";
+
 		green_pwm_led: green_pwm_led {
 			pwms = <&pwm2 2 PWM_MSEC(20) PWM_POLARITY_NORMAL>;
 		};

boards/st/nucleo_f303re/nucleo_f303re.dts

@@ -25,6 +25,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_2: led_2 {
 			gpios = <&gpioa 5 GPIO_ACTIVE_HIGH>;
 			label = "User LD2";
@@ -33,6 +34,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "User";
 			gpios = <&gpioc 13 GPIO_ACTIVE_LOW>;

boards/st/nucleo_f334r8/nucleo_f334r8.dts

@@ -24,6 +24,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_2: led_2 {
 			gpios = <&gpioa 5 GPIO_ACTIVE_HIGH>;
 			label = "User LD2";
@@ -32,6 +33,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "User";
 			gpios = <&gpioc 13 GPIO_ACTIVE_LOW>;
@@ -127,7 +129,6 @@
 };
 
 &flash0 {
-
 	partitions {
 		compatible = "fixed-partitions";
 		#address-cells = <1>;

boards/st/stm32373c_eval/stm32373c_eval.dts

@@ -22,6 +22,7 @@
 
 	leds {
 		compatible = "gpio-leds";
+
 		green_led_2: led_2 {
 			gpios = <&gpioc 1 GPIO_ACTIVE_HIGH>;
 			label = "User LD2";
@@ -30,6 +31,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "Key";
 			gpios = <&gpioa 2 GPIO_ACTIVE_LOW>;

boards/st/stm32f3_disco/stm32f3_disco.dts

@@ -23,34 +23,42 @@
 
 	leds {
 		compatible = "gpio-leds";
+
 		red_led_3: led_3 {
 			gpios = <&gpioe 9 GPIO_ACTIVE_HIGH>;
 			label = "User LD3";
 		};
+
 		blue_led_4: led_4 {
 			gpios = <&gpioe 8 GPIO_ACTIVE_HIGH>;
 			label = "User LD4";
 		};
+
 		orange_led_5: led_5 {
 			gpios = <&gpioe 10 GPIO_ACTIVE_HIGH>;
 			label = "User LD5";
 		};
+
 		green_led_6: led_6 {
 			gpios = <&gpioe 15 GPIO_ACTIVE_HIGH>;
 			label = "User LD6";
 		};
+
 		green_led_7: led_7 {
 			gpios = <&gpioe 11 GPIO_ACTIVE_HIGH>;
 			label = "User LD7";
 		};
+
 		orange_led_8: led_8 {
 			gpios = <&gpioe 14 GPIO_ACTIVE_HIGH>;
 			label = "User LD8";
 		};
+
 		blue_led_9: led_9 {
 			gpios = <&gpioe 12 GPIO_ACTIVE_HIGH>;
 			label = "User LD9";
 		};
+
 		red_led_10: led_10 {
 			gpios = <&gpioe 13 GPIO_ACTIVE_HIGH>;
 			label = "User LD10";
@@ -59,6 +67,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "User";
 			gpios = <&gpioa 0 GPIO_ACTIVE_HIGH>;
@@ -188,7 +197,6 @@ zephyr_udc0: &usb {
 };
 
 &flash0 {
-
 	partitions {
 		compatible = "fixed-partitions";
 		#address-cells = <1>;
@@ -209,6 +217,7 @@ zephyr_udc0: &usb {
 &timers1 {
 	st,prescaler = <10000>;
 	status = "okay";
+
 	pwm1: pwm {
 		status = "okay";
 		pinctrl-0 = <&tim1_ch1_pa8>;