boards: Convert stm32h750b_dk to HWM v2

Port the board to HWMv2.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>

boards/boards_legacy/arm/stm32h750b_dk/Kconfig.defconfig

@@ -1,11 +0,0 @@
-# STM32H750B DK board configuration
-
-# Copyright (c) 2023 STMicroelectronics
-# SPDX-License-Identifier: Apache-2.0
-
-if BOARD_STM32H750B_DK
-
-config BOARD
-	default "stm32h750b_dk"
-
-endif # BOARD_STM32H750B_DK

boards/st/stm32h750b_dk/Kconfig.stm32h750b_dk

@@ -1,8 +1,5 @@
-# STM32H735G Discovery board configuration
-
 # Copyright (c) 2023 STMicroelectronics
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_STM32H750B_DK
-	bool "STM32H750B Discovery Kit"
-	depends on SOC_STM32H750XX
+	select SOC_STM32H750XX

boards/st/stm32h750b_dk/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: stm32h750b_dk
+  vendor: st
+  socs:
+    - name: stm32h750xx

boards/st/stm32h750b_dk/doc/index.rst

@@ -59,8 +59,8 @@ The current Zephyr stm32h750b_dk board configuration supports the following hard
 
 Other hardware features are not yet supported on Zephyr porting.
 
-The default configuration per core can be found in the defconfig file:
-``boards/arm/stm32h750b_dk/stm32h750b_dk_defconfig``
+The default configuration can be found in the defconfig file:
+:zephyr_file:`boards/st/stm32h750b_dk/stm32h750b_dk_defconfig`
 
 Pin Mapping
 ===========

boards/st/stm32h750b_dk/stm32h750b_dk_defconfig

@@ -1,9 +1,6 @@
 # Copyright (c) 2023 STMicroelectronics
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_SOC_SERIES_STM32H7X=y
-CONFIG_SOC_STM32H750XX=y
-
 # Enable the internal SMPS regulator
 CONFIG_POWER_SUPPLY_LDO=y