boards: Convert stm32g071b_disco to HWM v2

Port the board to HWMv2.

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

boards/boards_legacy/arm/stm32g071b_disco/Kconfig.defconfig

@@ -1,11 +0,0 @@
-# STM32G071B Discovery board configuration
-
-# Copyright 2021 The Chromium OS Authors
-# SPDX-License-Identifier: Apache-2.0
-
-if BOARD_STM32G071B_DISCO
-
-config BOARD
-	default "stm32g071b_disco"
-
-endif # BOARD_STM32G071B_DISCO

boards/st/stm32g071b_disco/Kconfig.stm32g071b_disco

@@ -1,8 +1,5 @@
-# STM32G071B Discovery board configuration
-
 # Copyright 2021 The Chromium OS Authors
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_STM32G071B_DISCO
-	bool "STM32G071B Discovery Board"
-	depends on SOC_STM32G071XX
+	select SOC_STM32G071XX

boards/st/stm32g071b_disco/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: stm32g071b_disco
+  vendor: st
+  socs:
+    - name: stm32g071xx

boards/st/stm32g071b_disco/stm32g071b_disco_defconfig

@@ -2,9 +2,6 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_SOC_SERIES_STM32G0X=y
-CONFIG_SOC_STM32G071XX=y
-
 # Serial Drivers
 CONFIG_SERIAL=y
 CONFIG_UART_INTERRUPT_DRIVEN=y