boards: Convert nucleo_g031k8 to HWM v2

Port the board to HWMv2.

Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>

boards/boards_legacy/arm/nucleo_g031k8/Kconfig.board

@@ -1,8 +0,0 @@
-# STM32 Nucleo-32 development board with STM32G031K8 MCU configuration
-
-# Copyright (c) 2022 Joylab AG <team@joylab.ch>
-# SPDX-License-Identifier: Apache-2.0
-
-config BOARD_NUCLEO_G031K8
-	bool "NUCLEO-32 G031K8 Development Board"
-	depends on SOC_STM32G031XX

boards/st/nucleo_g031k8/Kconfig.defconfig

@@ -5,9 +5,6 @@
 
 if BOARD_NUCLEO_G031K8
 
-config BOARD
-	default "nucleo_g031k8"
-
 config SPI_STM32_INTERRUPT
 	default y
 	depends on SPI

boards/st/nucleo_g031k8/Kconfig.nucleo_g031k8

@@ -0,0 +1,5 @@
+# Copyright (c) 2022 Joylab AG <team@joylab.ch>
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_NUCLEO_G031K8
+	select SOC_STM32G031XX

boards/st/nucleo_g031k8/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: nucleo_g031k8
+  vendor: st
+  socs:
+    - name: stm32g031xx

boards/st/nucleo_g031k8/nucleo_g031k8_defconfig

@@ -1,11 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-# Zephyr Kernel Configuration
-CONFIG_SOC_SERIES_STM32G0X=y
-
-# Platform Configuration
-CONFIG_SOC_STM32G031XX=y
-
 # Kernel Options due to Low Memory (8k)
 CONFIG_MAIN_STACK_SIZE=640
 CONFIG_IDLE_STACK_SIZE=200