boards: Convert olimex_stm32_e407 to HWM v2

Port the board to HWMv2.

Signed-off-by: Abderrahmane Jarmouni <abderrahmane.jarmouni-ext@st.com>

boards/boards_legacy/arm/olimex_stm32_e407/Kconfig.defconfig

@@ -1,11 +0,0 @@
-# OLIMEX-STM32-E407 board configuration
-
-# Copyright (c) 2017, Erwin Rol <erwin@erwinrol.com>
-# SPDX-License-Identifier: Apache-2.0
-
-if BOARD_OLIMEX_STM32_E407
-
-config BOARD
-	default "olimex_stm32_e407"
-
-endif # BOARD_OLIMEX_STM32_E407

boards/olimex/olimex_stm32_e407/Kconfig.olimex_stm32_e407

@@ -1,8 +1,5 @@
-# OLIMEX-STM32-E407 board configuration
-
 # Copyright (c) 2017, Erwin Rol <erwin@erwinrol.com>
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_OLIMEX_STM32_E407
-	bool "OLIMEX-STM32-E407 Development Board"
-	depends on SOC_STM32F407XG
+	select SOC_STM32F407XG

boards/olimex/olimex_stm32_e407/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: olimex_stm32_e407
+  vendor: olimex
+  socs:
+    - name: stm32f407xx

boards/olimex/olimex_stm32_e407/olimex_stm32_e407_defconfig

@@ -1,8 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_SOC_SERIES_STM32F4X=y
-CONFIG_SOC_STM32F407XG=y
-
 # Enable MPU
 CONFIG_ARM_MPU=y