boards: st: fix STM32C0 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]:
- 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 <[email protected]>

Author: etienne-lms

boards/st/nucleo_c031c6/nucleo_c031c6.dts

@@ -23,6 +23,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_4: led_4 {
 			gpios = <&gpioa 5 GPIO_ACTIVE_HIGH>;
 			label = "User LD4";
@@ -39,6 +40,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "user button";
 			gpios = <&gpioc 13 GPIO_ACTIVE_LOW>;

boards/st/nucleo_c071rb/nucleo_c071rb.dts

@@ -23,6 +23,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_1: led_1 {
 			gpios = <&gpioa 5 GPIO_ACTIVE_HIGH>;
 			label = "User LD1";
@@ -44,6 +45,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		user_button: button {
 			label = "user button";
 			gpios = <&gpioc 13 GPIO_ACTIVE_LOW>;

boards/st/stm32c0116_dk/stm32c0116_dk.dts

@@ -22,6 +22,7 @@
 
 	leds: leds {
 		compatible = "gpio-leds";
+
 		green_led_3: led_3 {
 			gpios = <&gpiob 6 GPIO_ACTIVE_LOW>;
 			label = "User LD3";
@@ -38,6 +39,7 @@
 
 	gpio_keys {
 		compatible = "gpio-keys";
+
 		reset_button: button {
 			label = "reset button";
 			gpios = <&gpiof 2 GPIO_ACTIVE_LOW>;
@@ -156,7 +158,6 @@
 		zephyr,resolution = <12>;
 		zephyr,vref-mv = <3300>;
 	};
-
 };
 
 &die_temp {