boards: Convert stm32l1_disco to HWM v2

Port the board to HWMv2.

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

boards/boards_legacy/arm/stm32l1_disco/Kconfig.defconfig

@@ -1,11 +0,0 @@
-# Board configuration
-
-# Copyright (c) 2019 eTactica ehf
-# SPDX-License-Identifier: Apache-2.0
-
-if BOARD_STM32L1_DISCO
-
-config BOARD
-	default "stm32l1_disco"
-
-endif # BOARD_STM32L1_DISCO

boards/st/stm32l1_disco/Kconfig.stm32l1_disco

@@ -1,8 +1,5 @@
-# Board configuration
-
 # Copyright (c) 2019 eTactica ehf
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_STM32L1_DISCO
-	bool "STM32L1DISCOVERY Development Board"
-	depends on SOC_STM32L151XB
+	select SOC_STM32L151XB

boards/st/stm32l1_disco/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: stm32l1_disco
+  vendor: st
+  socs:
+    - name: stm32l151xb

boards/st/stm32l1_disco/stm32l1_disco_defconfig

@@ -1,8 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_SOC_SERIES_STM32L1X=y
-CONFIG_SOC_STM32L151XB=y
-
 # enable uart driver
 CONFIG_SERIAL=y